10.9 compression ? Are you sure about that ?
What head gaskets ? I am running same kit with 65cc w2 heads and I calculate right around 10.9 IIRC ....
one of us is wrong
My heads have had significant milling. Prior to the milling the engine was 9.8 or 9.9 to 1 i believe. My engine builder did the calculations not me but I'd assume he's correct. He's been doing it for 35+ years and he's really good at it. Won the Mopar engine builder challenge and does many a professional drag race motors.