For those interested in the Z8 wheel:
I found a comment in a forum saying that:
"the Z8 steering wheel and airbag is a direct fit for the 2002 Z3. so, i guess as long as you have a 2001-2002 Z3 with dual stage airbag, the slipring, airbag, and wheel is just a simple swap."
That means,you could go to any srap yard or BMW-Dealer to test if the BMW Z3 wheel fits and if so, order the Z8 wheel.