I don't know if this problem has raised it ugly head and I don't have the time over here to read through all this thread but when reading the last couple of postings, I notice the name Iwis crop up.
The chains that I used to get off Alan the chain man were marked Jwis and were made in Germany.
I seem to remember contacting Alan regarding primary chains for high performance use and I'm sure he said he could supply primary chains for competition use in the CB750 but they weren't the Jwis chains that I used on my other bikes so I'm not a lot of help on that but just in case you're wondering, Iwis and Jwis are the same company so don't be put off by the slight difference in the name.
Sorry I couldn't remember this earlier when we were speaking Rafi but that's just my head problem, sorry mate.
Sam.