Before you invest in any more head scratching about temperature, see if you can get "real" temperature readings, like an infrared gun arrangement, or tapping off to a new digital gauge. There are all sorts of reasons why you might get a hot reading, real or imagined. My 49 has run hot at times for 1) failing water pump 2) failing thermostat failing to circulate water at the RIGHT speed to get maximum heat transfer through the radiator--especially noticeable when FINE at 45-50 and suddenly HOT at 55-60 3) radiator which flowed fine but had an insulating coating on the original rad 4) wonky carburator running too lean 5) ignition too advanced at times 6) tight engine after rebuild.7) failing grounds on wires/sender. I most be a poster child for all the problems.
Oh wait, isn't pump cavitation another problem that would suddenly appear under slightly higher RPMs when it might not be an issue at iddle or at moderate load and speed?
Besides, Continental engines "can" run warm especially if you are running them at high--for them--RPM. If ever there was an automobile that liked a winding two lane highway and overdrive, its a Kaiser/Frazer.
Just saying, maybe your car is hot, maybe its not.