An angle grinder with a cupped coarse bristle wire wheel will make short work of any caked grease, and rust plus get the surfaces right down to bare metal if you choose to. My go to for cleaning up a old dirty, rusty engine, of course have a good grasp on the grinder when using it on irregular surfaces. It's messy, but most any option, even pressure washing is going to be messy.
I just bought a pressure washer last year, but haven't tried it out on any greasy engines yet. It's a commercial 13 HP 4200 PSI unit, so it should be able to dislodge most any caked on gunk off of an engine.
