Strip paint from accessory drive housings?

I?m trying to tidy up the last few parts for my engine build before ordering the new parts and lining up a build day. I have the drives for the prop governor and vacuum pump (aux alternator, in reality). I?m trying to get them cleaned up and ready for paint with the rest of the engine halves but getting the paint off of them is a real pain because of the rough casting surface and all the complex curves. I got most of the vacuum drive cleaned up with a bunch of MEK and scotchbrite but it?s really rough and some Lycoming gray is still left.

Is it really important to completely strip the paint off these before repainting? Or can I just get the loose parts up and clean well, then repaint? Note I?m only talking about the housings for the governor and vacuum drive; the case halves and accessory case were fully stripped when I bought them and my sump will be new.