Modern vehicles have coolant temps above 200*, which is bad for a transmission. These older Fords usually run coolant in the 190's, rarely a person chooses a 180 T'stat and has it below 190.
I couldn't get a useful answer about what an ideal ATF fluid should be, but I think it's between 120* and 150* or so. So aiming for that is tough given the radiator ATF path, and typical Winter or Summer outside temps.
I will make an attempt to install a thermostat device in my trans line. If it works to install a marine T'stat "pill" into an oil thermostatic bypass adapter, than I can keep ATF temps close to the 145* range, where the T'stat will open. If that works, then anyone can choose to skip the radiator, and maximize the cooler sizing, still ending up with predictable ATF temps.