Thicker head gaskets/ less compression...
Your engine with aluminum heads should not ping with a 509.
Did you give any thought to a better carb.
I responded to you in the other post....
10.7 with aluminum is like 9.7 with a steel head.
I run 9.5 comp.with a steel head and the smaller .484 purple cam and can run 89 pump gas.
If it pings real bad i would think your engine is of a higher compression ratio then you think????
BUT...If your sure it's 10.7 then try a better carb before tearing into your engine.