The front brakes on Boxsters can easily go between S and Non S versions (simply bolt on). Going beyond that is unknown to me other than the brembo kits you see for 4k everywhere.
Your kit is obviously different. Try parts heaven for some used ones (hub carriers). Someone has got these I'm sure. How about Carnewal in Europe? There are lot's of places to try before machining your own. Pick up and Excellence, GT, and Porsche and 911 world magazines from your local Borders book store and start calling and emailing....happy hunting
