I had a 1994 van at one time. I was on my third transmission by that mileage and had to rebuild the rear axle once. Aside from that, the van was bulletproof. By comparison, my current van, albeit with only 300,000 km, is still on its original 4r100 transmission and one replacement rear axle. I tow a lot of miles with heavy trailers, which likely accelerated the failures, but I'd still suggest closely looking at the transmission fluid color, shift quality, and ability to pull in overdrive; the E4OD transmission did not match well with the diesel engine.
As for the engine itself, I would strongly recommend testing the coolant:
The 7.3L IDI was susceptible to cavitation...you can research that if you are not familiar. It is remedied by adding a supplemental coolant additive (SCA) to the engine coolant on a regular basis. It can also remedied by replacing the engine if SCA is not added. If the coolant test strips indicate that molybdate or nitrite are low, I would pass on the vehicle, as it probably means the van was not properly maintained.
BrianW makes a good point about parts availability. Most of the Ford parts should be easy enough to get, but the Quigley 4x4 parts would almost certainly have to come from the US via air freight. Very carefully inspect the front suspension, front brakes and steering components. If anything is even slightly worn, make sure to price that in to the amount you offer for the van. Make sure that the 4wd actually works, too. Believe me, I know how much it costs to ship heavy suspension components outside of the US.
Finally, if you buy the van, put that Haynes manual in the recycle bin and buy some Helms factory service manuals on EBay.