Since I'm right in the middle of a Golf conversion myself I will add my two
cents.  The wiring loom wasn't that hard on the Golf, stripped out a bunch
of wires but the ones needed for the fuel injection seemed pretty obvious.
Wires for lights and other no related things seemed to only run in the same
wire-looms and didn't attach to any of the wiring for the fuel injection,
other then grounds.
The big headache I have found with the Golf conversion is getting the
intake manifold to fit and the placement of the Cis-e fuel distributer.
I've looked at the Subaru conversion and it looks like everything fits
pretty nicely without having to cut any holes in the bus.  Other then the
wiring I think this is probably a much easier conversion, especially since
you can buy a complete kit, so you don't have to go out and fabricate a
bunch of stuff like the exhaust, etc. etc.
The reason I went with the Golf over the Subaru was that I already had the
pieces to mount the Golf being that my Vanagon was a diesel.  The other
swaying factor was I had a friend who had a Golf GT that had a good engine
but had been hit several times, so I could get a low cost engine, with a
know history.
Dave K.