Hey, Mad Dog1
If that Winchester M94 is a pre-1964 model, refinishing is NO problem. Either conventional hot tank bluing or color case hardening are viable choices.
However, if it is a post-64 model, you could have some real problems. For many years, the post-64 M94 receivers were made from a sintered metal (powdered metal alloy casting) and presents some real headaches for gunsmith refinishers. The problems encountered included uneven coloring, with red, green or gray splotches. Some were even "black chromium" plated, which defies all attempts at hot tank bluing.
I dunno about recent (since the middle 1980's production, but all I have seen look like conventional bluing or industrial black oxide and you should have no problems with those.
You might try researching on the Web and asking refinishing specialists.