@jeffrey-white   I had a similar issue with my 37 with a newly rebuilt 235 and a new radiator.  It would blow coolant out the overflow tube and past the cap and drench the underside of the car with coolant.  It would continue to do this until the coolant level was so low that the engine temperature would start to increase (low on coolant).  I bought one of those combustion gas detector kits and tested the engine maybe a dozen times.  It never failed a test.  I finally purchased one of those after market overflow tank kits that mount on the firewall and I have never had another issue.  Radiator is always full, car runs consistently at about 160, even in 95 degree weather, and I have no coolant leaks.  I can't explain it but I did fix it.

@ole-olson I think you could add the early 4 cyl chevys to that list. And strangely my parts book for 29-32 list a thermostat and in bold letters advises NOT to use one with cars with a heater. Also I think the first hot water heaters from Chevrolet came out in 32. Maybe one of our cooling system experts will "chip"
 in and enlighten us.

Update:  I tightened the water pump packing nut just a little.   Also installed a temporary mechanical temp gauge so I could monitor the temp.  The original gauge is not working.   Took it for a 3-4 mile drive and the temp got up to 180 and stayed there while driving.   It did creep up to 220 after shutting it off which I’m guessing is normal when the circulation stops.   It did not puke any antifreeze after I shut it off this time.  There was some foaming in the radiator when I first started it up.  What is the normal operating temp for these engines?   

@jeffrey-white The normal temp is determined by the "thermostat" being used but I think the 180 is a little high . I run a 160 in my 32.