[spangy]

This fix would be relatively easy even without spare grips. There are a few different ways to tackle it but I don't think I would use the spare grip unless I had to. G.T. will tell you that any fix requires patience and planing. Lack of patience is the primary enemy of quality repair ... without it you may as well not bother. Having said that this repair looks like fun to me, to others it looks like a headache .... don't use those type of people for the fix.
Tom Austin has an excellent point in that the chip is part of this gun's history and as such adds it's own element to the gun's gestalt. Humans being the way we are like things as perfect as possible though and I get that.
Good luck with whatever you decide ... its an interesting dilemma.