You guys and gals are "up on the tire" with this young man. Well said everyone. Even a naturally-aspirated build will cost about $10 per hp. You should figure roughly $1,000 just for for machining and balancing if you're going to do it properly. Can you rebuild a motor on a tree stump with pliers and a screwdriver for less? Yes, of course you can, but don't plan on 500 hp.