1937 212 overheating

Here are a couple more possibilities:

1). The sender (in the block) might be "lying" to you, indicating a much higher water temperature than is actually the case. If so, you need to know how accurate the sender is. Remove the sender from the block. The wire from the dash gauge should remain attached to the sender, and you will also need to ground the body of the sender to a ground somewhere on the car. Heat some water in a pan, along with a thermometer to measure the water's temperature. Heat the water to a known temperature, and then immerse the sensor rod) in the heated water. Turn on the car's ignition and observe the needle the dashboard temp gauge. (Obviously, the car should be parked near your pan of heated water, for this test to work!) The normal water temp operating range is 195°F – 220°F. So, when the water in the pan reaches about 220 degrees, the dash gauge should be reading somewhere in the mid-range. If not, replace with NOS (if you can find one for a '37 Terraplane, ha-ha!).

2). The thermostat in your engine may not be fully opening, thus constricting the flow of water. Prepare a test pan with water and thermometer, as above. (You won't need electrical hookup for this test). Remove thermostat from engine and immerse it in a pan of heated water. Observe the movement of the thermostat. At what temperature does the thermostat open, and does it open fully? How smooth is the action? The old style brass thermostats are still around for purchase, if you need one.