Generally, insurance companies don't care what kind of powerplant you have in
your vehicle as long as it's not bigger (like in more cylinders) than your
old one IF you only have liability coverage.

However, if you expect them to cover you for comprehensive and collision, you
best tell them the cost of the conversion and maybe pay the extra cost of
coverage. Otherwise, they will pay you the basic cost of an unaltered Vanagon
if your vehicle ever gets totaled. (That may actually be a higher value than
your conversion -- <lol>).

BenT
San Francisco