At those hours I would bet the cam is gone. If you do buy it take off a barrel and have a look. 1200 for a cam plus lifters. Case needs to be split. Flat tappet valve trains don't last long. New rings for sure 600 bucks. . Barrels should be fine and the heads and valves should be fine as would be the bottom end. Gearbox service is easy as. You need some special tools which you can buy from bert flood.
Remember don't hone those cylinders. Crc and and a clean rag is all they need.
Also don't touch the valves. They are non serviable. Valve stem seals. New colets. Check your heads for hardness. Media blast them and if you want a very light hand lap on the seats.
Lyndon