WFH8ZIT,
Try to be more specific in your information given. "built 302" and "Carbed 351", are gonna cut it. There are plenty of 302 based engines that can hand A LOT of 351 based engines their asses. A 351 based engine will ALWAYS have more POTENTIAL that a 302 based engine based on cubic inch potential, but if you don't do the neccessary steps in terms of component matching, etc., you could end up with a 351 thats a turd as well.
Do you have a displacement in mind for the 351?
What parts would you be buying for the 351 based engine (Heads, cam, crank, rods, pistons, intake, compression, etc.)?
What does the 302 have in it (Heads, cam, crank, rods, pistons, intake, compression, etc.)?
What kind of budget are you on (in school, working, parents are loaded, etc.)?