I haven't heard anything bad about Pro Parts, but I haven't used them. The guy who runs it autocrosses with SCCA in SoCal. I did request a quote online to rebuild and revalve my Konis and got a quick response. I ended up getting Bilsteins for my car instead though. My Konis didn't last very long before one started leaking, and they're more expensive to rebuild and revalve than the Bilsteins.
You can also send them to Koni North America for rebuild and revalve.
Make sure you request dyno charts (and post them here when you get them back!). Ask the shock technician to adjust each pair until they match on the dyno, and then mark that adjustment. Don't change it.
[This message has been edited by Steven Snyder (edited 04-03-2014).]