Since the shock isn't concentric with the spring, my gut feel is that even
though they look a bit odd at full droop, they are probably ok.  I would only
worry about it if I were lowering the van and the shock allowed enough travel
that the springs might fall out.  I'm looking at this from a 2WD standpoint,
though, as I've never seen a Syncro .  My Carat rears will rattle around at full
droop, so I'd want to make sure the springs stayed put with the Burley setup.  I
would think the selection of 2.5" springs would vast from a place like
TrueChoice, etc.  (If they're still in business!)

 Chris