I replaced my pump recently, on an 87 2.1 non-syncro, and did not remove
the main pulley.  I removed the connection to the passenger side head
and pushed the pipe over and behind the pulley.  Putting the new pump on
wasn't exactly easy, but it was possible.

Hint: To get to the 6mm allen bolts on the hose on the left side (toward
the main pulley) of the pump take a standard 6mm "L" shaped allen wrench
and grind about 10mm off of the short end.  It will make the job a lot
easier.

dave
www.251.org