Since Model 29 barrels are not hard to come by, why not take the idea from Drew to use a second barrel for the cut-down project. That way if the idea does turn sour, you can always put your old favorite back like it was.

Hamilton Bowen is not far from you. He is not "cheap," but he knows how to do this kind of work as well as, or better than, anyone. The nickel plating sounds like something that will have to be done at the factory, so I would find a barrel, get Hamilton to do the metal work for you, then ship it to S&W for the nickel. When it comes back, Hamilton can re-install the front sight so you will have a proper job. (The sight will have to be pinned. You do not want the gun nickel plated with the sight attached.)