Thanks very much for your reply Joe smile

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.