radiator highth

My radiator sits lower than my engine in my conversion car.I was told that I could cover the fill neck and put a hose fitting at the top and run it up above the engine to a small tank with a fill neck on it getting the radiator cap higher than the engine.Makes sence....but should I run a small hose from the thermostat housing up there too?Just to make sure I get any air out?The top hose goes downhill to the radiator.
Or will all the air be pushed out by the pump when the engine is started and replaced with coolant by the higher mounted small tank?