That thought had crossed my mind as well, even though they are from different decades. VR6 engines are commonly swapped into other VW models, so junkyards are well versed in pulling the engine, the engine wiring, and all associated electronics. The diesel tranny would probably easily handle the torque from the VR6 - even if the VR6 was warmed up a bit over the stock 170 HP.

It's a fun engine - the 15 degree cylinder banks lend it a slightly ruff and gruff idle, it pull strongly from off idle up to about 4000 rpm, where it comes into tune with the cam and intake manifold, and pulls like a banshee up to the 6500 rpm cutoff. It's smooth enough that you hit the fuel cutoff without feeling you are abusing the engine at all. Great howl out the exhaust too!

It probably wouldn't be much of a space problem to fit one in where a b18/20 once sat - it isn't any longer and barely wider - the intake manifold wraps over the top of the engine instead of just sticking out on one side. Its probably not a lot heavier either, despite the iron block.