Question 1; On my stock engine with enhanced bolt on parts, no cam change, I found .055 to perform the best, your results may vary.
Question 2; Stock heat range unless you have upped the anti with more compression, cam, cylinder head, intake, carb, headers, etc.... then you might find 1 or 2 cooler plugs help.
“You don’t want to get stranded? Then leave the OEM ignition box hooked up Incase of a MSD failure.
MSD was widely known as;
