67 Cuda Cooling

My 67 Commando has never had overheating problems. It has a factory 68 340 radiator (due to an accident, but that's basically the same as the 273 3-row), and a 7 blade fan, with no shroud. I have taken it to track days and run mountain rallies. So you seem to have something else going on. Start with the fan and water pump, I think.