In my opinion, having done one, the VW inline four swap is the best bang for the buck. And the many four cylinder water-cooled VW's I have had over the last twenty something years have been rock solid reliable engines. The key to it being less costly than other swaps is finding the original diesel Vanagon engine mounting hardware-usually sells complete for $400 to $600 and can be found at local wrecking yards from time to time. 2.0 liter four cylinder engines were the base vw engine throughout the nineties so are plentiful. 
As for the nissan V-6 in the Vanagon, I have seen one here in Santa Fe put together by a mechanic in Las Vegas, NV.� I can find his name if someone is interested. The work looked better than factory original, but to make that beast fit, required many modifications to the body under and around the�
 rear seat. It has been a few years, so my memory has faded, but it didn't look easy or straightforward like a VW four, or Subbie, or Bostig.
� 
I must say how I have appreciated this list, thanks to Jim and all those responsible and please keep it going. A bit of grumbling about the form is a pity, I am entertained and amused by the content no matter the form. And I suspect that most are like me and don't give a hoot about NVC once in a while, or top-posting versus bottom-posting, or any of the various issues causing the walls to come tumbling down.

Sam M.
1991 carat
1981 westy

>then you must be in California. .........so that gives you
>Subaru............and another choice, VW inline 2.0 liter 4.
>Not sure what years those start, but there might be OBD-I versions, which
>you could get through a Ca Smog Referee.
>Not sure how well they fit, but I'd love to do a Nissan V-6 engine
>conversion in a vanagon. it's been done......
>seems to me it would be one
 rugged long-lasting vanagon engine.