Full gun reblue would do more harm to guns value than a well fit pin. But, if you wanted the pin polished a good smith could mask of the rest of the gun, Carefully sand and polish the sides of the ramp at the pin. Then use a quality cold blue where finish is effected. Another option would be to mask of the gun with duct tape. Tig weld the blade tip and then file it close, sand it smooth and only refinish the blade. He could even dunk the sight in a hot blue tank with the barrel and ramp taped off.

Once the orginal finish is messed witth it is gone.