What degree Thermostat?

First, I don't agree with StrokerScamp's description, and I am sure others would agree that the thermostat's function is the regulate the water temperature leaving the engine at close its temperature rating, though the exact controlled temperature varies with the thermal load (lookup "proportional offset").

I recently changed the thermostat in my 64 Dart 225 because I wanted a 195 F thermostat. I found it already had a 195 F thermostat installed. Indeed, rockauto listed that as the standard temp, which surprised me since I thought factory was 180 F in those years. The higher temp was certainly standard in the 80's slant six. It reduces emissions and gives more mileage, at the loss of a little horsepower at WOT due to the less dense intake air and slightly more propensity for spark knock. I doubt a 195 F thermostat would exacerbate over-heating since by the time the cap vents it should be fully open anyway, and we can all agree with StrokerScamp that when the thermostat is full open it doesn't matter whether it is marked 180 F or 195 F.