Major 2 are When were the injectors serviced last and has the IP had a rebuild. how difficult and rattelly it is on startup stone cold is a good test to see what itsb fuel system is like. then theres the usual of general servicing (oil, filters, coolant, etc). Those Era transits also use bolts to hold the manifold on which snap off in the head so an exhaust leak is a bit of a major to fix. There is a company here in christchurch called All Transit Parts which would be a useful contact for spares. Rear brakes trake a hammering for some reason too.
I refuse to work on them now as most are neglected pieces of shit. Especially if theyre a camper van.