Dissapointing performance

For what it may be worth, I have not been able to follow all of this thread, but I recomputed the SCR and DCR with the latest data provided by the OP and come up with 9.9 SCR and 8.1 DCR. If all of the cylinders pressures are around 170 psi, then this all makes sense and indicates that the cam timing is probably pretty close to correct (106 ICL).

This ought to be a pretty torquey engine if the ignition timing is close to correct. Low RPM torque should not be badly lowered by the exhaust restrictions. But not being able to spin the tires says there may be problems with either the rear gear or the low RPM torque converter.

OP, is this TC an electric lockup type? You mention that it is a custom made TC with lockup? Can you provide more information on this TC?

And BTW, OP, with the heads shaved to 65 cc, the chambers are smaller and so typically a few degrees less ignition advance is needed.

I am a bit confused on the heads. Can you describe them in more detial? I thought these were RHS with 62 cc chambers but then you list the heads as being shaved to have 65 cc chambers.