Big difference between road race and autocross. If you want to road race in something like NASA (www.nasaforums.com), you'll need to start out with High Performance Driving Events (HPDE) - levels 1 through 4 - then get your competition license before you can do real wheel to wheel racing.

I wouldn't worry too much about hp at this point. See if you can take more weight out of the car, and make sure you have enough brakes to stop it - I'd be looking for 13" x 1.25" rotors up front and maybe 11.75 x .810 or larger in the rear. Wilwood makes good stuff at at affordable price - check their FSL calipers - about $150 each.

I'd go 17 x 9 on wheels, if you can fit 'em. You can get name brand lightweight wheels for about $125 each.

Detroit TrueTrac is a good diff for road racing.

If you've got an auto trans that's fine for autox, but I'd swap to a manual for road racing.

FYI - I'm in the middle of a 71 Javelin build for NASA American Iron - 401 w/500 flywheel hp, T-10, 9" floater w/Detroit TrueTrac, 3.50 gear, full cage, stripped interior, 17 x 9 wheels (MB Weapons, maybe?), street legal but with minimal creature comforts.

Good luck,

Scott