ahh Jimmy I don't know why people keep telling me it's not possible to find honest friends in internet forums!
The funny part is: I got this tank from ebay and it was advertised as "fuel tank for youngtimer". Without the words "Cafe Racer" or "honda cb" nobody found the tank and I got it for 130 Euros. There was a second tank from the same company on ebay advertised as "fuel tank for Honda cb500/550" in a slightly better condition but with the key missing which got sold for 505 Euros!! The only difference is that I have to fabricate some mounting points. But with 375 Euros left I can make them from gold ;-)