Big horsepower 318 builds

When I started this thread I was thinking 400+ horse. A horse/cube is fairly easy. A 400 horse teen is 1.25/cube. Hot Rod did it with cast Magnum heads back in the day. It should be fairly easy to do with the cam/valve train and heads now days. I should have posted 400+ as a guide. I don't know where the 500 horse thing came from. It can be done but it will have to be pretty sophisticated, expensive and probably not pump gas friendly and streetable.