Born in 2002. It was running sweetly on one cylinder then the previous owner was doing something (removing the carburettors?) which needed the exhaust removed so someone snapped all the 4 exhaust studs, they then started to drill out the studs and realised it was a crap idea with the engine still on the bike so left it alone in a nice dry garage for a while. The head needs to be removed and Mr. Exhauststud Remover can then mill the broken stud bits out. I'll need to go check what is in the cardboard box of bits which it came with to see if there's any new bits as well.
A second hand head is in the £100 to £200 range, a new one about £600. It needs another header pipe which are about £120 second hand.