Thanks guys, stripped the camshaft today. Shaft is bent and badly worn. 25 thou wear at the injector pump end, 6 thou at the other end. Add to this probably half as much again in wear in the bushes. Inlet and exhaust cam lobes look ok, a quick measure with a vernier calliper gives 314 thou lift on the inlet and 412 thou on the exhaust. The injector pump/oil pump lobe is history(poor lubrication and water ingress).
New bushes are readily available, a replacement shaft is not. I could go down the route followed by Dieselspanner and turn down the ends of the shaft and then make custom bushes or I could make a new shaft. I am tempted to make a new shaft, 7/8" ground silver steel is available from the UK and the holes are all in line so there would be no need for indexing.
I have no idea as to what the original shaft was made of, probably some sort of Sheffield steel, would silver steel hardened and tempered be a good replacement or would it be too brittle and break.