Hi Uwe,
I would get in contact with these guys:
http://www.helix-autosport.com/home.
Telephone: +44(0)1295 701076, sales@helix-autosport.com.
I used them a couple of years ago and they machined a roller release bearing for me and upgraded my standard MGB clutch to mate against my 4600cc block.
Tell them what you need and they'll suggest something for you.
All the best
Lawrence.