The rust can be readily removed by soaking the gun in moonshine. At that point, it should be safe to fire. These early parkers did not need barrels, as the cartridges were metal and that contained the shot.
As to the stock, after 28 days in Moonshine it will come out gleaming. The only caveat is that these guns must be kept in the dark. If you take them out in the light they will immediately revert to corroded. If you leave it in the box and do not look at it, however, it will be in as new condition.
As to a value, we should be able to digitally apply a Hilbert Transform to the image to recover the serial number. I have it from a reputable source who spoke to Elvis recently in a Laundromat that this gun was the very one Washington carried when he crossed the Delaware. I expect it will easily exceed the price for the Bo Whoop gun which also required some stock work after having been lost.
