Are you going to PC the rear spring black?
I know for a fact, you can paint the spring with fusion paint and then reinstall without knocking it off (within reason) as long as you let it dry out in the sun for a day or two first.
I painted my 400ex shock yellow. It looks ok, I dropped it against the vise once and hit a little spot off but it looks ok (especially considering it took about 4 minutes and cost me $.85)