Cheers for the replies.
I was thinking of powder coating over painting because I thought that would be a more robust finish, and because there's a few powder-coaters near me. I'm open-minded though - happy to take advice
The trouble is now the wheels and (probably tomorrow) the forks are off, I can see other bits that would benefit from a deep clean. The bottom yoke and swing-arm spring to mind.
At this rate, I'll have the whole bike dismantled and spread across the garage floor !!!