Some guys near Cologne did this swap. I found an article in 'VW Scene'.
Not very technical, but there is a picture showing the engine inside
the engine compartment. It extends about 20 cm above the bay lid. But
the mechanic had to built an own adapterplate to fit the engine and
bellhousing. Not an easy choice of an engine swap.

Helmut
'80 Camper
 ----------
>From: 74301.2203
To: Multiple recipients of list
Subject: VR6 in a Vanagon?
Date: Saturday, 07 Jun, 1997 14:25

Has anyone taken a look at the VR6 engine as a power source for the Vanagon?

Charles "Luke" Lukey
 Windup Technology, Inc.
 Seattle, WA