1979 Ford LTD Radiator not circulating.

I recently purchased this 1979 Ford LTD as a cheap run around car. When I was driving it home it overheated on me. I have changed the thermostat, water pump, several hoses, and had the radiator checked out. It was flow checked and was flowing at 85%. Also, the heater does not blow any hot air. I removed the thermostat and got the car home without it overheating. After I replaced the thermostat, the radiator does not flow and boils over after the engine gets hot. Both upper and lower radiator hoses as well as the upper and lower heater hoses seem to be getting hot when the engine gets hot. The question is, why is the radiator not flowing?