Cooling System vs Outside Temps

[31 Model A]

How much, on an average, higher per degree of temp outside would the temp rise in the cooling system? Anyone ever figure something like this out before?
Of course it depends a lot on the rad, water pump; etc but saying the WP and the rad are good, the system was flushed out.......etc etc. Starting point 75 degrees outside temp, rad temp is 150, running with distilled water after it warms up and after a few miles, then same condition but outside temp is 90 and the system has 50/50 anti-freeze? How much of an increase in the rad temp would there be?