Step 1: Clean
 

Before beginning tear down how are you cleaning the motor and tranny? Put on stand and spray with degreaser with a drip pan underneath?

I haven't begun my first rebuild (really close) but I was thinking of taking it to the local car wash and pressure washing it on the back of my truck. I would remove the intake manifold first and tape up the inlets to the heads.

If you go with a water based system...you have just hours to completely disassemble before the rust starts!
Hot tanking might be a solution.
Bob

I disassembled mine as it was and then hot tanked the parts....

I am unsure how far you are going to tear down the engine: but if you're doing a soup-to-nuts tear down (splitting the case), I would recommend that you pull it a part and clean them in a hot bath when separated/dissasembled.

If you're just doing a top end - I would cover critical areas and give it a start with carb cleaner and/or brake cleaner and a tooth brush.

I am not much a fan of using water or a pressure washer to clean the engine parts whole or in parts.

Good luck!