When I raced with the Jubilee in the late 70's, I couldn't use the long hanger bolt because the locknut on the back of the derailleur hanger would interfere with the 6 speed freewheel. I solved the pivot problem by drilling a small hole on the front edge of the Campy-style hanger. The hole would be perpendicular to and intersect the threaded hole of the hanger. I then tapped the hole for a tiny metric set-screw. The Jubilee was installed with just a bit of play that allowed the derailleur to pivot, and then the set-screw was tightened against the hanger bolt threads to lock it in place. It was a fairly elegant and unobtrusive solution to the problem, and worked like a charm.
Kevin Ko
Eugene, OR USA