FWIW, there probably are at least several hundred Vanagons on the road
now with 15" front disc brakes and stock rear brakes.  I don't remember
any discussion of this creating any problems for any one.

I think it would be most important to upgrade all of the rear parts to
new condition and fully bleed the system after putting the new and
larger brakes on the front.  If balance is a problem, and I am not
convinced it is in this application, old rear parts and fluid would sure
make it worse.

Just my $.002 worth of commentary.  (No, I didn't accidentally put in an
extra zero.  This is recognition that I am somewhat shooting from the
hip and don't have any real expertise on this.)

Sam

--
Sam Walters

Baltimore, MD