If that gun came into my possession, I would use one of the DIY stripping kits like those from Brownell's and get rid of the rest of the nickel. Then I would have the outside parts lightly bead blasted just enough to even up the surface. I'm too old school to use one of the painted finishes, but would go with a hot immersion or DIY cold blue, then re-oil the existing wood grips on it and throw it in my car as a ccw. That's my story and I'm sticking to it!
Froggie