buy a 460 its cheaper, well let me put it a different way. I assume you intend to do heads and cam and crank, and pistons and blah blah blah. that costs alot of money, if you have the money already set aside. then you spend an extra couple hundred to pick up a 460, essentially do the same work, spend the same money, and get alot better results.
Ie 502ci powerhouse
then again my mostly stock 429 already pushes 380hp with 480 ftlbs, more than enough motor for me, and I got it for an old set of 31's off my old man