Paint off engine

As I've been cleaning up the old Z, one of the things that has really been bugging me is the patchy paint on the fins on engine. There are also some bits on other parts of the engine that seem to flake off pretty easily, so I shouldn't have any trouble getting them off, but the really tricky bits are on the fins on the outside of cylinders (see below).
Any suggestions for effective ways to remove the paint that don't require me to take the engine apart and won't cause any other damage?
Any suggestions for effective ways to remove the paint that don't require me to take the engine apart and won't cause any other damage?