when did compression checks it was always a tad over 150# with stock domed pistons and composite 318 head gaskets at3.90 bore fire ring. I believe compressed gasket was approx .039. I thought compression would be more that 8.8
I looked up an ESSO tune up guide for a "1967" 273 Commando and it lists compression check from 130-165 psi minimum variation of 25 psi. 1966 for the same engine is 150-180 psi and a 2 barrel 273 as 120-150 psi.