Uwe - with that cam, a steel gear should be OK, but check with the cam and the distributor manufacturer helplines.
I still think that the high
oil pressure you set is the root of the problem. It multiplies the torque that the gear must transmit.
Be happy - you are the first Cleveland owner here that I know of with this problem! You are therefore unique. Have you tried the Cleveland engine forum at
http://www.network54.com/Hide/Forum/119419?it=0
( don't get me wrong - I am very sympathetic to how you must be feeling right now, but it IS part and parcel of Cobra ownership).