Ok guys. No one here really had a solution for me, so this morning I dropped by my local Chevy dealer and asked for a mechanic (actually asked for a hot rodder). The guy I talked to was a mechanic and fellow motorhead and SBC expert. I told him I had converted the vette over to HEI and needed to know what spark plugs to use in my 64' fuelie heads. He suggested that I use the ACDelco R45S. It is a hotter plug than the R44's I had in the engine before and the ceramic electrode on the R45S protrudes further out into the combustion chamber. He predicted correctly that the existing plugs were carboning up and said I was probably getting insufficient combustion and strong fumes from the exhaust. He was dead right on that. Man it would make youe eyes burn it was so strong! The carbonization buildup on the plugs is the result of the reformulated gas that the EPA has foisted on the Dallas area. He said the new gas was harder to ignite and doesn't burn as well as the gas used years ago. I asked about platinum plugs and said he wouldn't recommend them for my application because if they ever did carbon up they would quit working permanently. Thought I would pass this along to the forum.