Stroker 340>416 Build Advice
That was a special piston with a dome. The we a flat top piston Rod lower compression. With a 65 cc head and the flat top piston at a zero deck height and a .039 head gasket you’ll be at 9.8-1. If the piston sits down in the hole some, the ratio will be less. You can also use a thicker head gasket to raise the cylinder head to lower the ratio.