Well, well,well.
At least you gave us a tranny. If that low gear 904(2.74-1.54-1.00) has a loc-up, Shazzam!! The ratios are a bit better than a regular 904(2.45-1.34-1.00).A well built (not over-cammed)teener will have no problem with the splits. But the 12% better first gear really helps an LC teener or big-cammed teener. 12% is about 2 diff sizes, and turns a 3.23 into a 3.61, a 3.55 into a 3.97, and a 3.91 into 4.37.
I already discovered, for me, that 4.37 is a terrible street gear for a stick car. I can't see it being any better on an automatic.
A LC street-teener likes a starter gear of about 11.0 to 1.With the 2.74 tranny gear, this works out to......11/2.74=4.01; which I would round down to 3.91s. But if you bring the compression up;a 10.0 to 1 starter gear works pretty good. That would then be 3.65s, which could be rounded either way; 3.55s or 3.73s. You could match the 3.73s with a stockish TC (depending on your cam), or go 3.55s with a slightly looser TC. Since Ima willing to bet you're gonna go with a loose TC,in any case, I'd go 3.55s. Plus if you don't like those , they're easy to sell.
But if you're sharp on the engine rebuild, bringing the Dcr up to where it needs to be, then the extra torque by that move, can be used to motivate the car instead of gears and hi-stalls.And that may allow a 1size smaller diff.
-3.23s aint't all THAT bad with a sharp Hi-comp teener, a low first gear and a nice TC.
The starter gear works out to 3.23 x 2.74 x TCratio = 8.85 x about 1.1 = 9.74. Thats pretty close to 10.0/1. Of course the 3.55s will multiply the engine torque another 10% which could be 30 to 40 ftlbs,more. Yummy.
-The point is this; build the engine first. Build it right. Then let it tell you what rear gear it wants. Thats my opinion.I didn't vote.