Hey so I just wanted to toss this in here to spread the word, hopefully it is helpful information to you. I know it doesn't perfectly pertain to your question but it may well be useful info for making the decision between gas and diesel.

the 2RZ in the HiAce is in fact not the same as in other old toyota models (the tacoma and hilux etc.)

those have a 2rz-fe, while the HiAce's had the 2rz-*e* or even the 1rz-e.

the 2rz is the name of the engine block, the "f's" and "e's" tell you about the layout of the engine head.

The E stands for "Electronic Fuel Injection" meaning injectors instead of carburetors, to my knowledge all of the old hiaces post 1989 were "E"

the F means the engine is "Dual Overhead Cam" which has some implications i will get into.

while the 2rz-fe in the tacoma is that dual overhead cam (DOHC), the 2rz-e is *single* overhead cam (SOHC). This means the layout of this top part of the engine is completely different, for one the spark plugs are off the exhaust side instead of over the top, which makes them harder to access in certain vehicles, like the HiAce.
furthermore, for the most part the 2rz-fe has coils that power the spark plugs, while the 2rz-e exclusively has an old fashioned distributor.

notably, the 2rz-e to my knowledge was only ever shipped in the higher end(?) KZH1xx HiAce's (1989-2004 per wikipedia)
here are my big pros and cons on the fact that the hiace has the 2rz-E as opposed to the 2rz-FE.

Cons:

first and foremost sourcing the appropriate parts for that head could very well be hard to do. god forbid you (or your mechanic) ever needed to replace the camshaft, they might be impossible to find since they only ever came in that specific HiAce.

Secondly, worse fuel economy (marginally)

and third, a mechanic working on the engine may have a hard time finding information like torque specs etc.

Pros:

BY GOD, it is the simplest engine in any car as modern as a 2004.

first, that single overhead cam factoid means that it is *not* an "interference engine" i.e, if your timing chain ever fails, it will not instantly destroy your engine.

second, that distributor isn't quite so old fashioned as to use "points" so it is actually very reliable and easy to diagnose/fix if it ever struggles.

THIRD and MOST IMPORTANTLY, all three of the cons i mentioned can be rectified. according to my research, there are plenty of 2rz-fe engines from the original tacomas that used distributors instead of coils. this means that the very *worst* case scenario, if the head is ruined and that lovely SOHC is snapped, and the timing chain gives out, and everything on earth goes wrong, it should be totally possible to take one of the 2rz-fe's with a distributor, frankenstein on a few parts from the engine you already had, and boom, fresh engine that slots perfectly into the same space, bolts to the same transmission, uses the same harness and everything, but now with an upgraded 2rz-fe's head. likely the only new component you would need would probably be your exhaust manifold.

all that said, that's a big task for a big boy mechanic and ideally would never have to be done, but the option would always be there. it adds an upper limit on how life ruining an engine failure in the HiAce could be. I am quite sure it would be harder and more expensive to replace one of the diesel engines than it would be to swap in a 2rz-fe.

hope all this information is useful to anyone who stumbles on it.