Karl, I made this swap on my '85 a few years ago.  I used the procedures at
www.oldvolkshome.com.  They talk about having to get a larger throttle body
but my '85 already had a large one installed.  I used the '85 cooling system
and the '85 FI system.  Worked great until the crank broke in the 2.1.  It
was an easy swap and I'll do it again when I get the $ for a Boston Bob
rebuild and core charge.  Ken at Vanagain and Boston Bob have ECU chips for
the 1.9 ECU that should provide even more power.

Tom
'71 Westy,
'85 Westy,
'87 Westy Auto,
'91 Carat,
'81 VW Diesel Pickup