Greetings! I did a conversion of 1.9 to 2.1 back in May.

I bought a Boston Engine 2.1l 1.9l equivalent engine.
http://www.bostonengine.com/

I was very impressed with the quality of the engine and with the help and
phone support Bob gave me during the install process. It took me 4 days to
do the whole thing, although I think you could do it in 3: I was working
pretty slowly.

The engine now has 10,000km (6200 miles) on it and is running very
smoothly.

I live in Alberta, and am an avid mountain biker, so all the driving I do
is long distance, high altitude punctuated with long/large hills...

I just returned from a 2000km (1200 miles) run out to Whistler BC and back,
which was the real test.  That trip takes you up Golden pass, Rogers pass
and the notorious Duffy Lake Road...The engine ran great for the entire
trip: even with the steep climbs and hot weather( temperatures getting up
into the 40c (104f) range through Kamloops/Lilooet/Pemberton).

I documented the entire engine removal/parts swap, install and other
related van adventures on my photography site:
http://www.cloakofcarrot.com
Detailed photographs of the installation and photos of the van in various
locations in the mountains are here:
http://www.cloakofcarrot.com/gallery/1985Westfaliavanengineinstallation

I am still running the original air intake system, since I didn't have
access and have not found an available 2.1l intake system as yet, so I am
probably not getting quite the full power out of the engine that I could. I
installed a K&N air filter though, and that made quite a large difference
in performance - especially on hills. If I do manage to track one down
though its on my list of things I would like to do to the van.

For my latest van project, I just finished installing the Vanagain.com
gastank and fuel supply fix kit, which has worked great - no more leaky
lines/gaskets around the tank.

Next project will be the front passenger heater core, which I
disconnected/bypassed when I did the engine install as it was leaking.
Since it was summer, I didn't feel like taking apart the dashboard at the
same time as tearing down the old engine - one major project at a time! So
I just put in a bypass hose that took it out of the cooling loop until I
get around to diving in and replacing the heater core..Which will have to
be before november - gets pretty darn cold here in the winter!