It's interesting that you mention 300ºF Steve, that's less than 150ºC, and I was already wary of the potential for destabilising the alloy. Hence the dashboard attempt. The two or three "expert" advisors who commented for heating in the oven have all been around the 180ºC mark. I always bring a large pinch of skepticism into the comments section because there's so much social proof based thinking out there that it's a dangerous thing to take anything as a given. A person sees a YT video showing how something's done, and that forever more is the right a proper way of doing it.
It wasn't very obvious but there are actually two attempts at the tool in the video Thomas, and the second one is cut down a good way to be both on the straight of the tool, and much closer to the pivot. I could go closer again though. What I also need to do is weld some webbing along the handles to make them rigid and transfer all squeezing force through to the head. I knew locking pliers were the ideal but I didn't have a suitable one I was willing to sacrifice.