Yes, the powerhead must be removed to drop the lower u it. This is the case with all of the 7.5s and 5.5s. Not a difficult job and it gives you the chance to renew the lower crankshaft seal components while you are working on it. New drive shaft to crankcase gasket and a new O-ring inside the carbon seal and a new powerhead base gasket along with the water pump impeller and gearcase seals and you should have a good reliable runner for a long time.
-Ben