So, from all of the OPs statements this sounds like a rough gun that would take a bit of work to restore. It will have little value as a historical piece. And, yes, any gun can be 'repaired' to shoot like new.
The question is, how much is the purchase price and how much would it cost to restore? If barrel can be recovered then will it shoot well enough to be worth it, or will it need to be bored and rifled (or relined)? Will the investment end up being more than buying another gun of equal vintage but better condition?
It all depends on what the OP is after.