If you depend on this van I'd do both heads. If one is leaking the other
probably isn't far away from leaking.  The best repair would be to replace the
heads. If money is tight use jb weld to fix the heads and get a gasket kit.
You can probably repair it for under $150.  I have had very good results with
this fix.

The bad portion of metal pipe could be cut out with a hacksaw and then find
hose of suitable diameter to replace it with.  Put a couple of clamps on,
refill coolant and your back in business.

Hope this helps
Chris