I have one I bought new in 1968, it was my coyote gun for many years, I killed a lot of dogs with it, today she is mostly a safe queen as I now use a 22-250 or .223 for dogs.. There is still plenty of ammo available for it, check auctionarms web site, also check Midway, they have it in stock.
It sounds like you made a good deal on the gun, I’m sure you will enjoy it.