[piecesparts]

It is a fact: The hotter the spark, the larger the gap is desired. This is how the later model vehicles are set up to get a cleaner burn of the lower grade fuels. On my 383 stroker engine, I run a Carb Shop built HEI with 8 MM wilres and Accel plugs (to get the shorter porcelein body for my headers(, the ones that I use are the same heat range as the AC R45TS plugs. I set my gap at .045 and have had no issues with the engine. I do run my timing at a higher setting than most, but I get decent mileage and good horsepower.
If you want to think a littler further outside the box. Consider setting up a MSD 6AL multi-spark unit and get a more complete burn on your fuel and ilk out every ounce of energy out of each gallon of gas.