Unless you just like to do the work as a hobby (and there's nothing wrong with that), putting the work into the gun and expecting to Profit from your time spent is not a good bet IMO.

Even the thought that making it more presentable would make it sell faster might not be so true as there are a good number of originals in nice shape around yet at decent prices in 12ga.

Better to sell it as-is to someone else looking to do the same IMO.

They are good solid shotguns. Many are used for conversions to double rifles and that one would be a good start towards one for someone contemplating such a project.