Gear ratio help

First, don't pay too much. 7 1/4s are almost give away. I'd say $100 tops for an open diff; the sure-grips are another matter.

If you come across a newer one, pay attention to the bolt pattern because I'm not sure when they switched from SBP to BBP, but someone here can provide the details. If you do in fact have SBP and you find a BBP rear for a good price, I think the axles are pretty easy to remove/replace on those.

And the later V8 cars may have a 7 1/4 as well. I have a '73 Swinger that's a 318 2bbl automatic and it's 7 1/4 2.76 from the factory. I'll be going to an 8 1/4 when I do the 4bbl swap, but for what you're doing there's really no point to anything bigger. But as AJ pointed out, finding one with a better gear ratio (higher numerically, assuming yous is a 2.xx) could be a nice upgrade.