What do you think of my build? 318/390

https://www.uempistons.com/index.php?main_page=product_piston_info&cPath=8_9_13&products_id=262
This will give you roughly 10.8:1 with 69cc chambers which is a little much.

Yea, I think 9.5:1 is probably the max I should go. I don't think there's a thick enough gasket to bring those pistons down to 9.5:1. Well, if I have to cut the heads then there may be no other way (although I could swap out the heads for some 360s with a smaller cc, if they make any). If I cut the heads I imagine I'll also have to cut the intake side as well. But at least I already have the adjustable rockers. You didn't put that in your list of parts, I've heard you need adj rockers if you cut the heads.

treblig