If you are not concerned about the paint or markings (if you're redoing that) brake cleaner to degunk. If you are concerned, try naptha for that purpose instead. You have to get it all cleaned up.
The best oil I've found is Micro-Kroil. Not easy to find. If you do the naptha cleaning, then there may be sufficient lubrication left to test run the clock but I wouldn't count on it for the long haul.
I got two standard and one rallye clock running using naptha and micro-Kroil. I _think_ one of them also required cleaning up the contact points, but its been so long I don't remember for certain.