Oh by the way for those that haven't rebuilt a A/C compressor I found a couple good videos while I was looking up the clutch bearing part numbers that are very helpful for anyone doing it for the first time. A quick note if you don't have good head pressure it is likely that you compressor has lost enough oil over the years that the pistons are worn out but there is still a chance that its just debris on the valve plates causing weak compression.
Video 1
http://www.youtube.com/watch?v=CD5lLC5v6PE
Video 2
http://www.youtube.com/watch?v=MangGmPZc6g