Even if financial considerations were not that important, I'd be tempted to only get it to firing condition and possibly preserve the remaining finish as is. I've got a couple of single shot shotguns from my great grandfather from back around 1900. They are in better shape than yours, and still are sound and fire, but I don't want to do anything beyond take care of them and keep them from getting worse.
These were mass produced single shot models, so even at that age, not a lot of monetary value in them, but it's a nice part of personal history to hold on to.