[randy500]

Maybe this will help. I have 2 big block '72 trucks and one small block.
'72 1/2ton no A/C the large heater hose goes to the water pump.
'72 3/4ton with A/C the heater hose goes to the radiator.
'72 1/2 ton 350 truck with A/C, heater hose goes to radiator.
I have a 71 small block and can check the heater hose arrangement on that tomorrow, it didn't have the 4 core radiator though so I think it wouldn't apply here.