I've had no misfires or any other ignition issues. That's why I went to .060 and not .065. I've got an MSD DIS 4 coming as added insurance. As far as the heat range, I'm also running a H20/methanol injection system. I don't have any detonation either. I've had plenty of experience with supercharged Mustangs. And yes I ran smaller gaps with those. If the ignition is strong enough run as big as you can til the boost can blow out the spark and then go back down. The amount of boost would also be a factor. Once you reach a certain level, then definitely you would have to go back down on the gap. You have to experiment to find the best settings.
1995 XLT 4x4 Supercharged 4.0. Lot's of stuff. Check profile.