hey i'm building an engine for my best friends 84 z28, it has 3.73 rear with a 5 speed. i was thinking to use one of the two combos, either use the stock pistons of an 87 350 which is a 9.3:1 compression, and use a comps roller cam with 276/282 duration and .502/.510 lift, and edelbrock intake and carb, or use hyper utectic pistons with a 9.72:1 compression ratioand bore out the block .030 over and use the same cam and the same intake and carb, or if any one els has a bette combo i can run plz tell me.

 

That cam's a bit big for compression that low. I'd get 10:1 with iron heads, or 11:1 with aluminum heads. Make sure this is the actual compression ratio too. Factory ratings tend to be very optimistic. I've often seen "9.5:1" motors spec out at 9.2:1 or lower. Small block Chevys tend to have the piston way too far down in the hole at TDC. Most "10:1" aftermarket pistons wind up in the low to mid 9s in reality.

Don't go overboard though. You still need the right amount of quench distance, or the piston will hit the head. You want about .035"-.040" for a steel rod street motor.