my87z is correct
what I said,heads = 60 plus hp.50 cubes will add 60 plus hp,torque would go up.
or like I said 60hp for better heads and maybe 20 more with a roller cam,thats 600,,,
blower or 496 will both need new pistons.
do the math on the cost of parts and see what works best for the situation? a 496 can use bigger heads than a 427 so more power potential there