500 hp 360 ??

With good machining and assembly, enough rpm, and the right cam it can make that figure with 250cfm heads. It's not "head limited". But you still have to Stage III port them and match the intake, buy good valvetrain parts, and fully machine the block, etc etc etc. That's why I say if he's earning a living doing this I find it hard to believe for that money. 400hp is easy for $4500. 500hp is another $1500-$2K and I still think that's getting out cheap.