I have used on the street 4.56 gears with 29 tall tire and it is no big deal. I currently have 4.10s in one car and 3.91 in the other and 3.55s in the 3rd. I will stick with the gears. I like response and you will not get the that with 3.55s in a heavy car A body fine B body no. I switched to set of 3.55s in my heavy 73 and took them out same day too much of low end difference may go back to 4.30s that I ran for 4 years I never have a issue holding 3500 + heck it blows the cob webs out drive it 55 miles to track one way If you need ear plugs your exhaust is too loud

I had 3.55's in my car with a lockup 904 and 27" tires and hated it. was tolerable on 55mph speed limit roads, but freeway speed limit in MI is 70, and ~3300 RPM (what it cranked along at ~70 mph) for any distance just wore me down.

I kept the gears, but added an A500, so my effective rear gear with OD is 2.45. much better.....

personally, I'd keep the rear gears you have, add a limited slip diff (I'd go with the torsen style offered by eaton, I think, if buying new), and high stall, relatively tight converter--one that will flash to ~2700-3000 RPM when you stomp on it, but not have a ton of slip at speed...