Right on about heat and squeeze for clearance. I use the correct outter diameter deep well socket layed sideways at the angle you need. Easy to make a professional looking depression in the tube. My RS header on my 64 is easily that close to the inner fender. It has never burned the paint, but it is a drag car. Try this If you decide to paint the headers insread of coating them . After cleaning , blasting, use metal prep on them . Last set of old rusty headers done this way made it 5 years still looking decent. As far as coatings, nobody better than QC Coatings in Michigan. This set shown for my wife's sb Challenger, 14 years old and were looking ratty. Not after QC tuned them up.
Doug
Doug