I was there, it was crazy hot on the gravel infield of the race track.

On the cooling, if the car cools back down when you slow down, then most likely it is a water pump or air flow problem. If it will not cool down unless you shut it off and let it cool, it is likely getting air locked. Still a flow problem but caused by trapped air in the system. When I first got my Coronet, it would do that at high speed and not recover, but it had a bad head gasket.