I would remove the shellac from the metal. I doubt that it has any ties to the working history of the gun and likely was applied to preserve it as a display item. The wood looks kind of touchy, I probably would leave that as is unless I had it in hand to evaluate it. I know a lot of folks would say leave it alone, you'll hurt its value. First, it isn't a high dollar piece so it's questionable how much it'll hurt it's value by stripping grandmaw's varnish job; second, it's been apart at least once and by a less than professional smith (see screw slots): third, it's yours to do with as you please. I seem to sense you would like to strip it and that might reveal some markings that will help identify its origins. I don't have any idea what was on both sides of the grip near the bottom but I feel it was on the gun when it was built.