340 coolant trouble

I fired up my motor tonight and ran into some trouble. Any help would be appreciated. The motor has been completely rebuilt at a local shop. Ran fine at the shop for long periods of time. Brought motor home installed it and now the problems start. Does not seem like the coolant is circulating at all. I removed the thermostat. Heater core hoses are hot. Radiator cap removed. Top radiator hose is hot. Lower radiator hose is cold. Fluid seems to be moving slow in radiator. I am thinking propellar busted or new water pump shot? Any ideas????