I also had the water pump go on my 1986 505 gas turbo. After looking around I found a shop near me, Arthur Gould Rebuilders, in Kings Park, NY that specializes in rebuilding old water pumps and mechanical fuel pumps.
They pressed it all apart, replaced all the bearings and seals and had it back to me in 1 week. They even made the gasket that I thought I would need to fabricate.
They are real nice and easy to work with, I am adding a link to their site if anyone else needs help.
http://arthurgouldrebuilders.com/
Steve
1986 peugeot 505 gas turbo
1959 bugeye sprite
2002 mini cooper s