5 Speed Gear ratio advice?

A to a starter gear
This is usually a compromise. First is the easiest to compromise cuz your usually just passing thru it on the way to somewhere else.
With a 4-gear
At the race track trapping in the right gear at the right rpm gets usually the lowest ET, so you gotta do what you gotta do, and first-gear is what it is
For a streeter second gear is usually the one to bias for, and since we really only have two low,s to choose from, again The starter gear gets compromised. I like to be dogging it at 30/35 in second gear, but have enough TM to keep up with traffics ups and downs. Shifting back and forth gets old. At the same time,when I backshift into first, I want the car to launch into next week! So I normally it's hard to do both. Then you add in cruising at a reasonable rpm, and it's all but impossible, to get a decent starter gear.
As to the engine
The more cubes you have or the smaller the cam, actually it's the VP that is of interest,, but the more VP you have, then the easier it is to get moving with a less than ideal starter gear.
And that is why I have a 367 with 10.9 Scr, and why I used to have a 223/230/110 cam. This combo gave me enough VP for a killer take off with a crappy starter gear. But when that cam died, I got greedy and installed a 230/237/110, and immediately I could feel the loss of VP. And that is when I began the hunt for the right starter gear. I eventually found it in a combination of trans,rear, and od.
So for me, it ended up with The 3.09-1.92-1.40-1.00-.78od and 3.55s This hit the most targets. This makes a starter of 10.97. This is pretty good making 4mph at 545rpm, walking speed. Of course the engine didn't like 545 with that 230 cam, so I had to work on that.But eventually I got her banging away reasonably happy. So for me the 10.697 is the bare minimum, cuz it makes 4 mph,doable. ZAnd it sets me up at 32 mph=4400rpm, ready to blast off,yet 32 is 2700 in second,reasonably quiet . and not sounding pretentious.and it sets me up for 93=5750 in third gear. And it sets me up for 65 =2870in fourth,and 65= 2236 in overdrive.So I'm hitting all the targets. With a 4+1.

So that brings us to 5-speeds
With a 5 you can hit more targets with less compromises.
To begin with there is about a 20% difference from trapping best in the 1/8 to trapping at the best in the qtr. so if your 4-5 split is neat 80% that's approaching perfect. Notice that LJ340 has a 3-4 split of 1/1.3=.77 which is close to perfect. And so with the right rear gear, he's all set to go racing, either venue, whereas the rest of us are swapping chunks or trapping off rpm.
Well it turns out that trapping at 112in the qtr usually takes 4.56s, or thereabouts. And so he's got a starter of 4.56 x 2.66=12.13 which is also pretty ideal for a track-car.
And finally he has a final drive ratio of 3.146 to cruise home at 65=2540 So,all-in-all a great combo, for a 340 with enough power to like 4.56s.
But if he only has power enough to like 4.88s then we are getting too much starter gear as a DD, and the hiway cruise is starting to buzzzzzzz.
But if he has a bit more power and can run 4.30s, Then the tranny is working better as a streeter, with only a little compromise as a streeter, so that's a good deal. But to really use those 4.30 that 340 is gonna be a bit of a brute on the street, or the chassis is gonna have to be lightened..4.30s are for cars that run closer to 120.

So now let's talk about your combo. What are your targets? Did you make any of those drawings yet? Re post #34
The typical starters are from 8.59 to 10.94, a spread of 27%. These represent 3.23s to 4.10s and the 2.66 low gear. you can fit just about any SBM streeter into there somewhere.
So,it turns out that there is about a 5 cam spread for a stick-shift streeter, running from 252 to 292. Middle of the bunch is about 272 then. If the Dcrs are well matched, then I'm gonna say a fun starter for a 340 is 9.77ish,right up the middle. This is a 2.66 x 3.73s for anyone following along. Now if you have a smaller cam or more cubes, you can go less. But a bigger cam or smaller cid, is gonna want more.
And if your Dcr is in the basement, then any combo is gonna want more starter.
I know my combo would be happy with 9.77 right up the middle..And I have a 367 with a 276 cam; so that would be right where the prattle predicts me to be.