re:  I have a 1980 air cooled automatic transmission Vanagon
and want to fit a 1990-1997 Jetta or golf engine

Think you'd be better off first getting a later vanagon
(water cooled since 83.5) that already has a radiator and
heater(s) and hoses running to them.  Also, I'd be surprised
if any conversion kits are made for auto trans.