318 driver - cam change or not?

Lessee you want around-town punch. And so far you have a smogger-teen with a 4bbl and dual exhaust.
But you are stuck with 2.76s and skinny 225/70-14s that won't spin. And probably a 1750 stall TC.
There is only one solution to this lack of punch; you need more low-rpm effective torque.
And there are just two ways to get it from the engine, and three more from the chassis.
As to the engine;
Stuck with the 1750TC and 2.76s, your only option is more cylinder pressure, and you will not get it with any bigger hydraulic cam. The solutions are higher compression pistons and or an earlier closing intake.
As to the chassis;
your options are; reduce the weight, increase the stall, and or increase the rear gear. And I recommend in that order.
As to weight; The 73 Duster is already a fairly light car, and has generous wheelwells which are gonna come in handy. There is not much in that car, for street, in Illinois, that you can sacrifice.
As to stall, I recommend a 2600 to 2800. I prefer the 2800.
As to gears; the sky is the limit but for a city car I recommend 3.73s or 3.91s preferred with the factory cam.

Now; if you do the stall and gears first............ then you can upcam, because the butter-soft bottom-end is bypassed with the higher stall TC. And with the bigger gears, whatever softness remains, is quickly overcome.
So in your case, you have to co-ordinate the TC and the cam,together at the same time... or just don't put a cam into it in the first place.
Think about it; the next bigger cam will move the power up about 200 rpm or 2 mph. With the 2.76s the power peak moves to about 52 mph. But the bottom end with the stock TC gets softer, that is to say more sucked out. Does that sound like a good solution? But guys just want to jump in with both feet, and grab a 262(or bigger)..... which is 22* degrees bigger than stock.. or 3 sizes. And so the powerpeak moves up ~600 higher than stock..... with the impossible to recover from, very soft, bottom end. Without going into the engine, there is only one bandaid for this condition, which is TM(TorqueMultiplication). And the starting point is a higher stall TC , like the same 600 at least; so 2350 at the minimum, just to retain the same low-rpm performance you now have. Bad deal in my opinion. Now with the 2.76s, and with the power having moved up 600 rpm or 6 mph; so now it is at 56 mph.
But you don't want just the same sucked out bottom end, so a 2800 is now the smallest to consider Stall, with a 3200 or more, a better yet solution with that 262 cam and 2.76s.
So you can see that this is becoming a balancing act, with lotsa money the solution.
Here's the deal; No matter how you look at it,your cammed up combo is gonna need a TC and gears anyway... so you might as well install them first, and maybe you will be so impressed with your smogger teen, that you will forget all about the cam idea. I can almost guarantee you this will happen with 4.30s and a 2800; cuz it did for me. And I'm crazy for smoking up the tires.
Grab a chair, I ain't finished yet.
Lemmee show you how this TM thing works.
Say your engine can make 150 ftlbs at 1750 at WOT, I mean let's just start there.
So then the TC is gonna multiply that, and the trans and the rear gears and by the time it comes to the tires, you might get;
150x 1.05x2.45x2.76 =1065 ftlbs of torque... which is pretty sucked out. Lets change the rear gear to 3.91s
150x1.05x2.45x3.91=1508, an increase of ~42%. That's pretty serious, but it will not sustain much tirespin. Ok so lets put the 2800TC in there. So this is about 1000rpm up higher on the torque curve, but with the stock cam,already on the downside of the curve, so I'll guess 240ftlbs Ok here we go;
240x1.05x2.45x3.91=2414ftlbs, now 127% more take-off torque, and now a serious tire-frier. You will need a Suregrip and much bigger tires to make use of that torque... and it's still the stock 8/1 smoggerteen with a 4bbl.
If you want to know; 150ftlbs at 1750rpm is 50 hp, and 240ftlbs at 2800 is 128 hp.

Now lets look at the engine;
Ok so here's what your smogger teen looks like with the factory 240/248/112 cam installed at split overlap or in at 110*
Static compression ratio of 8.0:1.
Ica of 50, 600ft elevation
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 7.04:1 .
Your dynamic cranking pressure is 135.08 PSI. .................. 135psi/111VP
V/P (Volume to Pressure Index) is 111
What's that mean? Well the cylinder pressure is extremely weak, so it will or should run on the crappiest gas imaginable. But it sure won't make much power. And the 111VP supports that with a zero tirespin, sucked out number of 111. Read about VP in the link in BLUE at the bottom of the page.
The cheapest solution to this is to advance the factory cam.
With stock exhaust manifolds, the overlap is dead so that gives you the freedom to advance thechit out of that cam, with very little loss of top-end power..... which you don't need top-end power with hiway gears anyhow how cuz 4400 is 50mph at the top of first gear with your 2.76s and 26.4 tires. Pretty much EVERY performance hydraulic cam that you might put into it , is gonna give up a lotta "no spin"bottom-end torque that you are already lacking.... to get some power at 50 mph, that you don't need, cuz you said "around town punch"
Did I understand you right?
Ok so lets advance the cam to in at 104, that's a lot; 8* from straight up, but only 6* from split-overlap
Static compression ratio of 8.0:1.
Ica of 44*, still 600ft
Effective stroke is 2.96 inches.
Your dynamic compression ratio is 7.25:1 .
Your dynamic cranking pressure is 140.55 PSI. ....................... 141/120VP
V/P (Volume to Pressure Index) is 120
What does it mean?
Well, the pressure has risen 4.4%, but the big deal is the VP has risen 8.1%., Making your engine feel that much bigger or more powerful. Lessee, lets add 8.1% to the 50 ftlbs with everything still as it is right now; 50x1.081=54 ftlbs, an increase of 4ftlbs. That doesn't look like much but remember all it cost you was a gasket. But hang on; that's at 1750 stall; what about at 2800, for instance?
Well; 1.081x240=259 which is plus 19.44, which is now a big deal, because, at the tires this translates to
259x1.05x2.45x2.76=28.4 EXTRA ftlbs, for the cost of a gasket and the time (and the tools if you have to buy them).
But what if you combine that with the 2800TC and say 3.73s?
Glad you asked;
259.44x1.05x2.45x3.73=2489, lookitthat, this retime was worth more than one full gear change from 3.91s to 3.73s
But hang on, Do you really need 3.73s?
No! 2489ftlbs is plenty of ftlbs to initiate tirespin with those skinny 225/70-14s, both of them,lol, probably to 25/30 mph,I'm guessing... so you could probably get away with 3.55s, or for a healthy squalk, maybe 3.23s. Lets look at the numbers with 3.23s;
259.44x1.05x2.45x3.23=2073ftlbs and IMO yes it will for sure bust 'em loose, but the spin won't go too far. How can I say this? Because there is something I saved for you. At zero mph there is a hydraulic TM factor inside the TC which can approach 2/1. Let's say your proposed 2800 comes in at just 1.8 at zero mph. Then
259.44x1.8x2.45x3.23=3696 ftlbs at zero mph. This is why automatic equipped cars can jump off the line the way that they do. A manual-trans car would need a rear gear of 3696/(259.44 x2.66)=5.356 to match that with the same engine.
This less squealing is kindof good cuz the cops are attracted to squealing tires. So your 60fts might improve with the 3.23s, but the run thru the gears to redline might be a tad slower. Since people are practically giving 3.23s away, I would try it, cuz they make hiway cruising to be more bearable; 65= 2675rpm at zero-slip, in your case.

Ok now recall I picked the torque numbers out of a hat, so while they may not be accurate, IMO, I think the results will be similar. Why do I say that? Cuz I have installed more than a few 2800s and 3.91s or better, and even without the cam re-time, customers always returned smiling; and the bigger the rear gear the bigger the smile. 4.30s are awesome. Heck you can take two plug wires off and with 4.30s still have fun.

Ok last bit; If you must have a cam... wait until after the TC and gears are in.... and get a solid flat-tappet cam to try to retain a modicum of cylinder pressure. Solids, net size for size, will close the intake sooner to help with the cylinder pressure thing.... which helps with the VP, which with just a 2800TC, could be useful at the lower rpms, while for sure it will make more power everywhere else as well.
Ok done