there are a number of engine swaps that are possible for a vanagon. while searching for info on possible engine swaps for my type3 I've seen a lot of info on the net for your kinda swap.
a VR6 will swap in fairly easily, I'm told it'll almost bolt right up.
a Turbocharged Subaru will fit nicely using a kenedy adaptor, lots of power to boot.
or you could go with a built up 2.8L type4 engine (
http://www.markstephenshp.com )
or a wasserboxer with dual turbos. theres a miriad of options, its just a question of how much money you have to play with.
I personally would stay away from 911 power, I think that you'd have problems with the cooling system/clearance issues. type4/914 power is a better Idea I think, but thats my opinion.
I was thinking of putting a VR6 into my type3 but though it might be a little overkill, but in a van the conversion would be perfect.
VB