Those heads will NOT make anywhere near as much power as the AFRs - not stock anyway. Also, those chambers will be too big for your LS1. If you get the 799 heads, figure at MINIMUM milling them. Milling will be required just to maintain a stock compression ratio, but it will limit the size of the cam you can run on stock pistons. The only way they will perform on par with the AFRs is with substantial milling and porting, and a good valve job. Not such the great deal you were expecting

 

Aren't the 799 chambers the same size as the 243 chambers at 65cc?

I thought they where, that'll bump your compression up a little from the 68cc 241 ls1 heads.

Now granted, it wouldn't be 59cc like most like to go...