You can just buy the head and plunger combination and not replace the entire pump. You know that right?
this guy sells a plethora of replicated parts at seafood dinner priceshttp://www.hansautoparts.com/1979-1984jetta.aspxmixed reviews, but it's an option
Should I test my spare pump? I will be swapping over my Caddy to a turbo starting this weekend. If I just took the working pump off of my truck and drained it would you be interested in that?