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
It makes sense because he has dished pistons. My previous motor was very similar and ended up about 10.8:1 (20cc dish, 57cc heads, zero deck, 4 inch stroke, 4.040 bore, 0.039 gasket).