High compression blues.

Just one thing for thought. Larger duration cams do bleed off compression ........at low rpm. The scavenging effects of long duration lots of overlap will actually build more compression at high rpm. That is why putting a big cam in your car tends to make it doggy off idle and pick up in the upper rpm range. This is where the OP is saying he has the pinging issue. Large cam may make it worse. His best bet would be eithe find some gas that can operate under these conditions or find thicker head gaskets to add ccs to the combustion chamber.

I have a motor in the works right now that I expect to have the same issues with. I have a .060 383 with 11.5 to 1 compression ratio. It is going in a car shortly.