Refinishing it won't add any more to its collector value, and would take
away something. Make sure you know why you want to have it
refinished.

As was suggested, the first thing to do is to get a letter on it, so
that you will know what you are destroying with a refinishing.

Assuming it has nothing special in its provenance, you would be be
better off selling it, and finding another in better condition. You didn't
say that the gun has any family significance, so why bother spending
money for no reason. Its not like 27's are scarce - there are lots of
them around.

Mike Priwer