A poser for ya

Neither. Coolant LEAVES the lower radiator hose, goes up through the pump, and flows into the block on both sides. It partially flows up into the head, but MOSTLY goes towards the rear of the block, coming up into the head at various points, and flowing FORWARD through BOTH heads. It comes OUT of BOTH heads in the front, "Y's" together in the crossover in the front of the manifold, and flows up through the thermostat and back to the radiator.