Engine running due to stall converter???

Hey all -

Engine running hot, that is.

I recently acquired a 67 Valiant, 360, 727, 3.91 with a 3800 stall converter. The car runs well and is pretty quick. The problem is that the engine temp will creep up while maintaining high speed (60mph). It will keep climbing until I come down to slower speeds. Then the electric fan is able to bring it back to 190'. My question is: do you all think the converter is causing the heat? I sure do. I've checked everything else like thermostat, coolant level, radiator and radiator hose blockages, etc. The only transmission cooler being used is the one in the radiator.

Your thoughts and ideas are welcome.
Thanks.

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