Funny thing this question. I have a close friend who just sold a Boss at the last Julia's Auction and it went for a tremendous amount. Even as much as the Boss over and under that was listed.
It was a surprise to him.
He is now convinced that original guns are bringing the top dolor. And that could be true. Poorly restored guns are terrible to look at and many time the work is undoable.
I have just recently purchased a nice London Best and have thought of some things I would like to do. Redo the case color, re-black the barrels and other hardware just to mention.
But I have decided to do only minor changes.
If you consider restoring your gun then pick someone who is excellent at doing it and can keep it at least close to the Maker's style.