Your gun appears to have the original nickel finish. I do not advise trying to polish it. It appears to be flaking near the muzzle in the ejection-side pic.
It's expensive, but guns in this condition can be stripped of the nickel plating and the flaked areas (only) polished to original specs. Then the gun can be replated in nickel. If done properly, the result is undetectable as a refinish.