3.55s are plenty of gear for an automatic, behind a torquey teener.
You would hate 4.56s within a few short hours.
But I assume you were kidding!
With 23.4s and the current 2.76s; your hiway Rs works out to 2973@75,locked up. At 75 the TC will very likely be locked up.For me this would be unacceptable. I would be trying to fit some 28.0s in the back, to bring the Rs down to 2485locked up.Even that is buzzy for me.
Should be able to get 26s-27s for not too much, they'll likely not fit up front (but may with the V8 bars your car has), but it should bring the RPMs down to something not out in left field. Rebuilding and swapping to an overdrive transmission from an '89-'95 truck would be a nice improvement that'd let you have your cake and eat it too. Steep 1st, steep 2nd, .69 overdrive. With 28.1s and a .67 overdrive I really liked the speeds with 3.73s in the mid-upper 70s. I think like 2250. An A500 "42RH" with 3.73s in an 8-1/4 or 8.8 would be a pretty nice setup for a cruiser. LSD- for a street car I'd let whatever you can get your hands on determine that. If a readily available axle doesn't have an LSD in it- you don't need one. If it does have it, run it.
But here in Manitoba the speed-limit is mostly 100kph, which is 62 mph. For me that would be 62@2054 and totally acceptable.And so that's what I got!A final drive of 2.769. And 3.55s out back; hooray for overdrive!
70 for most of the roads out here. So rolling out with traffic over that shouldn't ever be obnoxious. It very much falls into the category of no overdrive- don't spend the money to lower your fuel mileage and increase your RPMs. Sure it'll be more fun but not like it'll be without compromise- just gotta know what fits best into your needs.