I think I'll wait on the info that the engineering firm comes back with with regards to the crank and if it needs welding.  There were no thrust washers on the big end when we took the engine apart which was a little worrying. Also, some fool had cross threaded the drive side nut (left hand thread) and the nut was just rattling on the end of the thread! There was quite a bit of aluminium sludge in the cases from where the drive gear had been catching the clutch basket too... :-( the engineering shop said it shouldn't be too difficult in repairing that though.

Does anyone know the best place to get hold of these thrust washers then?

Thanks guys.