If I were you I would replace me Waterboxer with a nice 4.3 liter V6 Chevy.
The motor, parts and labor would be the same or less than getting a rebuilt
waterboxer put in your van by the dealer.  Think about it, power, reliability
and no more headgasket worries.  Why am I interested?  I hate to see people
throw their money down a rat hole.  It is not that I am against VW, I love VWs
but when I get letters from people all the time with this headgasket problem
and they have replaced the motor 3 times and the heads just started leaking
again (this was an actual letter I got) it calls for a change.  If you need
more info on the conversion write me back.
Hope I helped.
Ken Wilford
John 3:16