I would use either 160 or 180 degree thermostat. One downside to the 160 is the heater may not be as warm in the winter.

I prefer a 180 degree but my truck is driven in FL where outside temps are generally warm and my engine gets to temp in about 5 minutes.  I wouldn't go any lower than 160

@drtyler thanks Dane, the car stays in the garage for winter.

@dunfire thanks Patrick, I’m going with the 160 for now, if it doesn’t work I’ll change it.

@bruce-bernhjelm If the engine runs hot with a 160 thermostat, your car likely will need more cooling capacity. This assumes that the engine is properly turned up with regards to timing, valve adjustment, and carburetor.

I would recommend 180 deg. thermostat as a higher temperature increases the power slightly and the bulk temperature is still well below the boiling point for water and water with coolant added.