A suggestion:
Do NO cleaning or restoration work of any kind, until you can have someone who is very conversant with guns of that era examine the find.
Folks have posted about guns in that condition, and I see the general consensus is that if it's nasty, rusted up or without wood that it's worthless.
Here's a picture of a slightly rusted, discolored gun. Take a look at the pictures--then look at the price it sold for:
http://collectorebooks.com/gregg01/c...er/Lot-464.htm