I agree with the previous posters.

I'm running combo similar to yours and my pistons are .030" in the hole. Using the "McCandless method" of calculating compression ratio, mine is 10.87:1 with 84 cc heads and a .040" head gasket. (Why are there so many different ways to calculate CR?).

I put this engine together before cheap aluminum heads enabled us low income bottom feeders to have great heads at an affordable price, so for the first year or so I had ported 452's on the engine. It absolutely would NOT run on pump gas without pinging. I had to put 1-2 gallons of racing gas in every tankful to calm it down.

To be fair, this was before I had a wideband A/F meter, so I'm not sure the carb couldn't have been tweaked to help the situation. But suffice it to say, aluminum heads made all the difference in the world.

As soon as the Edelbrock released their aluminum heads, I bought a pair. I can now run on pump premium, no problem.

Jim