Where does the gauge point when the tractor is warmed up but not working hard?

I have heard of engines running on the warm side until they are broke in, due to the extra friction from the new rings and sleeves. Did you go with a stock piston and sleeve set, or did you do larger? More power means more heat.

Beyond that, I'm not sure what to tell you. I put a 160 thermostat in my White 2-155 thinking it would help, but all it did was run at 160 except on hot days, and then it would climb up just like it did with the 180. Once you have reached the capacity of the cooling system, that's when the heat builds. I will also add that it also is fairly common for the temperature to creep up on them on 90 degree days, just because the radiator can't put as much heat into air that is already hot. Oliver must have thought it was ok, or they would have put the red zone a little lower. Let me know what your meat thermometer shows for a temperature.