If the new owner wants to make that gun new again;
Take off the bands, and Reel Spool, give that think a flat sand with 320. Use some different diamter forms such as different diamter PVC Tubes, and maybe some wood dowels for inside the muzzle (like you'd find on a foam brush) for the recesses. Put the gun down on two higher forms like Blocks and put some Wax paper etc underneath so you don't get your table all sticky. Paint on a flood coat of Tung Oil onto 1/4 of the gun ie back top half, front top half. etc. Then take some 320 wetsand paper (wearing gloves) and rub in a wetsand slurry using the tung oil. Let it stand for a few minutes and then wipe it dry with a dry cotton cloth like an old t-shirt. Then repeat on the other three quadrants. (If you do the whole gun at once you might miss your window to wipe dry before it gels up too much. Use a few dry rags so that you are able to remove excess slurry.) Then let hang for 24 hours. Next day while hanging from the butt, give a flood coat of Tung Oil with a foam brush. Almost immediately, wipe the whole gun down with a few dry rags. Let hang for 24 hours. Repeat. Repeat. Repeat. After this gun should look new. You don't need to remove all the hardware unless you want to. Just paint around it. If you do want to remove all the hardware is more ideal. Take some 320 or 400 grit and run it through the track a few times at the end to remove any drips from track and to make it smooooth.