> I was considering ways to reduce engine noise and had a thought...
> Any thoughts or other suggestions would be appreciated.

I don't have any suggestions on how to do it, only want to add that it is
worthwhile doing.
I recently bought an 86 GL syncro 7 passenger. One of the previous owners
had added insulation Anywhere that it was possible.  And I mean everywhere.
Doors, under the seats, walls, floors, even extra rubber seals around all
the doors.
I would say that this is by far the quietest vanagon I have ever driven.
Very solid sound when you close the doors.  A pleasure to drive.

Gary
http://www.telusplanet.net/public/gary2a/rack/vanagonrack.htm