The front suspension appears to be off of a Chevy II (Nova?). Something heavier duty and more modern could be grafted on.
The actual front suspension is really unclear to me. The prototype used a Corvair front suspension with the track widened by cutting the crossmember and splicing in more tube, but the "production" units - which were built in several versions by several companies over the years - could have used anything.
Clear photos of the Corvair front suspension are easy to find, but I have seen no indication that it was specifically Chevy II components; however, that's about the right weight class and it would have followed the conventions of the time. There are detailed parts diagrams available of the Corvair and Corvan suspensions
. The Corvan/Greenbrier was the van version, and used some different components of the same general design - if they were sane (and they were) GM would have used stronger components in the van, and if the Ultra Van builder were rational (unknown) and the van components were available (likely, but maybe not), the Ultra Van would use those.
Whatever GM components were used, for at least part of the history of the Ultra Van the front suspension has custom-fabricated control arms
, intended to allow a greater steering angle than usual; in photos, they look longer. These look really good, but may be of questionable structural design and construction. In the linked forum discussion, the various component origins are given (including Chevy II spindles).
Whatever the original components, and whatever is in this vehicle now (previous owner modifications are likely), it certainly deserves careful examination and assessment. And the brakes are probably drums that are outright scary by today's standards.