Well, it won't blow anything up, but hose placement will dictate how well you heater works and wear on the core.

The inlet nipple is the lower one and the exit nipple is the upper. This forces the coolant flow to fight gravity to flow and forces any air out of the core.

The heater inlet (lower) is supplied by the outlet on the intake manifold, and the heater core outlet (upper) routes back to the water pump stem.