My main concern was getting everything clean and prepped in some of the hard to reach spots like between the fins and in grooves etc. I was also worried about the original paint flaking a little in parts that I couldn't sand.
I've cleaned everywhere as best as I can with a die grinder and a little abrasive pad and so far so good - it's in primer now. I think for my next one I'll strip the engine so that I can clean and prep everything thoroughly.