Thank you to everyone who has been so helpful, thanks to a Dutch member of the German forum I now have all the information I could ever need. In actual fact when I stripped the engine the problems became obvious, the piston was so tight in the bore that even with the rings off it needed a push to slide down the bore, an O ring had been left out of the rocker oil feed so the oil ran straight out of the rocker box again, consequently the valves were ruined. A case of built for show and not go I think. I am now fairly confident that with a little help from my friends I will have her running again as she should. I will keep you posted. Thanks once more, Pedro.