318 LA torque?

I have an 84 D100 with a 318LA, operating at 900ft elevation.
Here's my recipe; stock 1973 smogger-teen just freshened up. She's got a TQ on her with a small-port iron intake, dual exhaust, an A 998 TorqueFlite with 2.74-1.54-1.00 gears, a 2800 TC, and 3.55s with 28s. And she fries the tires in first gear and gets sideways at 30 mph.
That starter gear is 3.55x2.74x24/28=8.33 corrected to a 24" tire. With 31s you would need 3.91s to be about the same.
If you have an A833, you would need a bit more gear to compensate for the lack of the convertor, so figure 4.10s.
But if you have a NP 435 with a granny gear; for spirited driving,that will have to go.
If you do the 5.9 engine swap, the NP 435 will be the deal breaker, so get rid of it first (unless your primary concern is towing. And yur still gonna need the 4.10s. The Magnum is gonna need a 4bbl and intake,and also gonna need dual exhaust. Headers with that stock cam are optional.
So do yourself a favor and just do all that to your LA first, and see how that wakes her up..
Then if you feel like you need more, then, you can re-think the situation, having lost no money in the swaps.
But if you do the Magnum first, and then discover the need for gears and a different trans, where's that money coming from?
But if you are at over 5000ft, forget the stock LA; it has no cylinder pressure up there.

And finally; you are gonna need to do something with the rear suspension, cuz wheel-hop will rattle your fillings, and start your kidney stones moving out to your bladder, and you will wake up in the middle of the night thinking you are dying, and you cannot get to the hospital fast enough. After you get there, they will put you on the backburner cuz you ain't in fact dying, you just can't take the pain that lil rascal is giving you. About 30 or 40 minutes after arriving you will come out of the MRI machine and the tech will tell you there are 7 more stones in there, most are bigger than the 5mil you are passing, and btw; nurse, give this man some morphine. 30 minutes later; clink, that rascal falls into the toilet bowl and the morphine is just starting to dull your "discomfort".
Knowing about those 7 others now, you will be taking every precaution you can think of, to not have another one leave it's home base,lol.
Course if you're anything like me, you'll just preach to them and pee sand for a couple of days;which is an interesting feeling,lol.
Yeah so anyway here's what I'm saying;
with the 3.55s and 31s right now 55mph is 2120 rpm and your teener, at 2120 might have a max torque available of say about 200 ftlbs/80hp. So if your load is heavy enough, your LA will not maintain 55. By 65 the rpm is up to 2500, close to peak torque with a stock LA and maybe she's putting out 240ftlbs/114hp to the crank. But now wind-resistance is sucking up the power, and maybe she still doesn't tow the load. Jus saying.
But with 4.10s, the rpm at 55 will be 2450, and with the smaller amount of wind resistance, that same previously too-heavy load, will now maybe come along. And 65 will now be 2900, and maybe that LA will have enough power to tow that same previously too-heavy load.That's what TM(Torque Multiplication) will do for you.
Now in first gear, if you currently have a granny-geared NP435, with a low gear of around 4.5(I forget the ratios of that grain-truck trans), then with the 3.55s,your current road gear is, 13.69/1, corrected to a 24" tire. With the A833 this will drop to 2.66x4.10x24/31= 8.44; so that would be abit of a shock. But at least you can downshift into it ....