Thanks for everyone's input here, much appreciated. I think my take away will be along the lines of finding a inconspicuous catch can/ overflow tank small enough to fit in front of the radiator and behind the grill connected as described above so it sucks coolant back after cooldown. Hopefully larger than a beer can.
I would like to keep the car looking as original as possible to the casual observer. Sorry for the "BAD" info J. I believe some car show guy that told me about large washers to restrict coolant flow and led me to believe the car didn't incorporate thermostats back then. I'll probably look into putting them back in if for no other reason than to help restrict the coolant flow to the radiator during high rpms.
In my case, the contribution of the thermostat value (160 vs 190) to engine thermal efficiency is very low, at least the way I understand it. Please chime in if I'm wrong J. I blow through the temperature range that the thermostats do any control in less than a few minutes. What is the thermal efficiency of these old 85hp flatheads anyway? Less the 20%? Much more sensitive to engine performance is probably combustion efficiency. Beyond the manual choke, I'm ignorant of how best to approach that on these old engines.
Bullshark