Gogar, nice work!
Don't feel bad about not pre-cleaning the engine before you removed it. I purposely left the engine on my cab untouched because I wanted to take my time and suss out where exactly all of the oil leaks were coming from once I had my engine on the stand. It's a good opportunity to learn things.
It's amazing the amount of grease, grime and dirt that you will have removed from the engine and engine bay when you're done. Pounds, I would estimate.
It's the little things: One of the most rewarding parts of my rebuild was after I refitted the cam towers and heads, and installed new oil return tubes. That's when I realized, holy crap, this thing's coming together!
Have fun.
Brian