Heat control paste doesn't really control the heat; what it does is keep air away from the hot surface so the oxygen doesn't cause the steel to burn or change color and the bluing isn't damaged. It is not intended to be used instead of a heat sink, but as a supplement to it.
I always used those iron blocks for bending a bolt handle and that in itself, when clamped in a heavy vise, is a good heat sink. I also used an old ground rod shaped to fit the interior of the bolt (copper is a good conductor), plus wet cloths on the front of the blocks at the bolt lugs. I never used a heat paste and never had any problems. Of course I had to polish down the bolt after bending and/or reshaping.
FWIW, I don't like to weld on a bolt handle; I can turn down one and stretch it, reshape the knob or about anything else that can be done without taking a chance of a weld-on handle coming off. (I know yours would never come off, but I have seen a lot that did, which is why I always forged them down unless the customer demanded a weld-on job.
What I did use heat paste for was things like silver soldering sights and soldering shotgun choke devices, where I needed to keep the bluing from damage. I also used it on the inside of the barrel, again to keep oxygen in the air from damaging the bore.
Jim