On my zz502 I used a combo dynoed by Sallee Chevy. Upgrades included mild/basic porting on factory heads, matching to intake, and Crane 168731 cam, springs, and roller lifters. 850 carb. Headers. You might want to play with the ECU to increase fuel etc with these mods to take full advantage.

552 hp @ 5500 rpm and 572 lb-ft @ 4500 rpm.

Kitz