As far as the metal goes; I'm not so sure I'd go any farther than cleaning off the surface rust. With a little luck you're not looking at severe pitting here.
The wood? Clean the grunge off and out of the checkering and lets see what's below.
Admittedly I'm sort of a minimalist when it comes to a gun in this condition but It can only have its original finish once!
Jim

The 2nd Amendment IS an unalienable right.