I have a 1957 312cu with the G heads  and 570 cmf Holley on it with 3spd OD and a 3 bladed fan.  Runs great  does not over heat even with this 90 degree weather.   In slow traffic it pushes up pretty close to 200.  Which then when I park it must push it way up.  So was wondering if a 4 blade would help?  Or I could mount electric fan on radiator with thermostat as I have do on others that I had with heating issuse.  Would like some input to push me off fence.