With the economy like it is and all things considered--a 451 build with a stock 44o crank, good rods, any decent head and solid or solid roller is HARD to beat. I always question when a HP number is the target. A real 500 HP engine is a TON in a street machine. Many guys with big stroker street stuff just spin the hides off and never really get a good driver IMO. 451 is a winner, they rev like a chainsaw and are cheap and easy. We did a 406 CI, 383 crank, 400 block , Eddy head, solid cam that made over 600 HP on pump gas in the Amsoil Challenge--It is available as it came off the dyno