Since it looks pretty tarnished, you may want to try cleaning it up with electrolysis. I haven't done that yet, but there are a lot of good videos on how to do it. Another way to clean silver corrosion slowly is to wrap it in aluminum foil with a pinch of salt and then submerge it in some water that you boiled and let it sit for a while.
Anyways great find, I haven't got a standing liberty yet.
I usually tumble my wheats and they come out pretty good. For black crusty/tarnished silver I have tried the aluminum foil and salt method which is like a very slow motion electrolysis method. Then have tumbled some of the silver after that with pretty good results.