I've tried a few different types over the years and always come back to the same conclusion that the stock style copper plug always worked best. I would go with the motorcraft or autolite copper plug. Unless you were running or shooting nitrous than I would say drop the heat range and change the gap to .035. Since your not the stock setup is best.
What plug dimensions does it take for those heads? If it's like most other aftermarket heads, use Autolite 3924's unless you have really high compression, boost, or nitrous, then i'd say start with a 3922.
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