If you are going to paint it, why not put it in your tank and clean what you can, then flip it around to clean the part that was hanging out? If you get the classic shaded line developing on either end, it shouldn’t matter; since, you’ll paint it any way.
Rapidly rotating wires of any metal can still alter the original casting. If you don’t want to use electrolysis, Evaporust would probably be the better choice. Is there any paint on it now?
As far as the blood, there is iron in it too.