[Brian]

There a several different design radiators available for 35 Fords. At least one design places the top of the overflow tube directly under the filler cap. Problem then is, at high[er] engine speeds, the water pumps push coolant straight outta that tube, which pretty quickly lowers the coolant level quite substantially. Ford actually issued a service bulletin which addresses relocating said overflow tube to the very top of radiator. I have previously posted that information on here. Another purpose of the hose mounted thermostats in 35 Fords, is that they do provide a slight barrier to the uprushing flow of coolant into the radiator, just slightly slowing down that flow, which also lessens the tendency to push coolant outta the radiator.

In my 35, I am running the big top tank version of the radiator, along with having the top of the overflow tube at the highest point of the tank, also thermostats. I run the bottom of the overflow tube all the way to the bottom of a catchcan. The radiator cap MUST seal. Fill the radiator to the brim...what happens is as the coolant heats up, it expands...the expansion runs out of the overflow tube into the catchcan, [instead of onto the road as it would if the tube was merely open], and automatically syphons back into the radiator as the coolant cools. The result is that the radiator is always full, irrespective of engine temperature.
I drive my car; lots, including racing it. It never overheats, or uses coolant.