you could build a 351 and make 400rwhp n/a, but your deffinatly not going to retain the stock bottom end. if you do then you wont havea 400hp car for very long. lat time i saw Cody's car on the dyno (herecomestrouble) he put down really good numbers for his 302 and spectacular numbers with the juice.

302 will make 400rwhp but you wont see any street action with it like that kind of combo. just find a 302 and put in a good bottom end for a reasonable price and throw on a 100-150 shot and you could put down anywhere from 400-450rwhp.

you could always buy a 302 block and then a stroker kit from someone and make a 331 and then spray a small shot and make hella good power and still be able to drive it to work everyday. a good trickflow set-up from heads, upper&lower intake, and a nasty cam will make over 300 to the wheels and then your only a 100 shot wayay from your goal.