I am a little too ........saddistic.........The cam with the special world saving specs that are soo top secret the owner can not know what they are.............and deliver his special world saving cam back to him thru the biggest window in his shop,then get a cam with some bigger specs to bleed off some pressure............I have no patience for knowledge withholders,they ususally have no greatness of their own ,soo they hide the info in hopes that it makes them look special or knowledgable.................the guy needs his cam back anyway on account of he speced it wrong anyway ,because it does not work for what he speced it for.............I spec I would tell him to shove the cam where the sun dont shine and then maybe he could get personal and familiar with the proper specs for a street engine.

Now on to helping ,you are going to need as much info on the engine as possible,fuel ratio ,timing curve,cranking compression etc.....I hope Paul Kane sees this one ,as this is his specialty,the 385 series engines.

It may be just a few little adjustments here and there ,a little more fuel,a little less timing,a little different timing curve........you are running premium gas .....?
The builder could have put in massive dish pistons causing a quench issue ,but that is not likely ,because of the high cranking compression you talked about.
What does the fuel ratio look like a lean condition will cause pinging too.