All that I've done so far is to wipe the metal parts down with Ballistol. Some light rubbing with Ballistol on brown paper towel really didn't bring up any dirt or crud. As I said, the gun is really clean and appeared to have been little used and well taken care of until relatively recently. It also doesn't appear to have been coated with lacquer or linseed or anything to protect the case colors. I can try a little lacquer thinner on a sideplate, but I don't think there is anything there that will dissolve in solvent.
I have cleaned numerous guns in the past that had similar or worse patina using 0000 steel wool and oil or WD-40. Any colors that were hiding under the patina were either removed or left very faint like dark patches. But on those guns, the colors on the water table or inside the forearm iron were also mostly gone. I'm less inclined to do any hard rubbing on this one because I suspect there is a lot more that is worth trying to save. I'm wondering if the electrolysis method of rust removal would take away the patina and leave any case colors unharmed. These seem to be uncharted waters.
I never heard of the copper wool that Dave in Maine mentions. Sounds like something I'd like to try. I have used bronze wool in the past, but I haven't seen that for years either. Many thanks to all who have replied.
