I am looking at buying a 2.8 or 3.0 l GU and do a TD42 conversion either straight away if I pick up a GU with a dead motor our eventually when a good TD 42 turns up.

How many kms would you expect a 2.8 or 3.0 be good for? Assuming that the necessary precautions are taken to prolong their lives? There are plenty around the 300k mark. I may have to drive it around for a while.