Just shoot it, be a good caretaker, custodian, for it and let your heirs worry about it. Guns a terrible investments in all but the rarest cases. Stocks and bonds are better investments but very poor tools to shoot. While your gun is one you could enjoy, a lot of buyers will want more features like ejectors or higher grade of finish. Worse now buyers seem to think guns should all come with screw in chokes, adjustable stock or worse camouflaged finish or black finish. If records dont exist you have no certain options.