Well I've been digging through manuals, after going through 6 different manuals I cannot even find any reference to the choke cable at all, except on the dashboard layout diagram in the Operators Manuals. But there is no reference to it at all in the Parts Manuals. That said, I have to believe the cable is a VW part.
Aktiv gave a pretty extensive parts listing, but was always very sketchy about the VW engine, and didn't give parts for the engine. Because of that, and because the choke cable is not listed in the parts manuals (at least not anywhere I can find) then I am coming to the conclusion that the part is a VW part. And unfortunately, I don't have that part number.
I'd suggest you take it out and measure the broken cable, then call up some of the VW air cooled engine rebuilders and suppliers to get a part from one of them. Sorry I can't be more help.