My dad just bought a 1989 firebird with a 11:1 383 with comp package AFR 210 heads, a 750 carb, and a 236 242 @ .050 .540 lift hyd roller cam. The car made 444 rear wheel hp on pump gas. If you assume a 22% loss to the rear wheels through a turbo 350 and ford nine inch, that is 540 hp at the fly wheel. I beleive the motor is under cammed and woud make more hp with a bigger cam. Although the AFR 210's you are looking are the race ready and not comp package, I think the extra cubic inches along with having a bigger mechanical roller cam will more than make up for the lack of CNC porting. 550hp should be no problem with the AFRs and the components you have.