If this engine is a flathead 6 engines, some used a water distribution tube that ran from the water pump outlet to the back of the block. This distributed the water evenly to the exhaust valve and head area. If you have this tube, check to make sure it is intact. If the back of the engine starts to boil coolant it will reduce the heat transfer capability of the entire head.
Just an idea I thought of.
I don’t know much about a 1932, but I have a few thoughts so I’ll throw them in the ring.
What temnperature T-stat did you put in? I believe those engines/systems/radiator caps were designed to operate at lower temperatures than today’s systems. I seem to recall T-stats of 165 degrees even in the '60s. A modern 180 degree or higher T-stat might allow boil over through the radiator pressure cap. Which, by the way, have you tested?
Did you check the hoses to the floor heater and defroster? Did you check to see that the heater and defroster are not leaking?
In my 1948, it was a hose problem to the heater. I put in extra valves to be able to bypass the heater when not needed as well as replacing the hoses and putting rust paint on the heater and defroster.