I did this and it seems to work and beyond the fact that the Gods of Vintage Lightweight Correctness might be offended, can anyone tell me if this is ok...?
I took the cage off my NOS Campagnolo Rally derailleur and put it on my spiffy, shiny NR derailleur. Shifts that 14-28 freewheel perfectly. Looks like it belongs there, except that you all know it does not.
Worst case scenario is that there is a reason why Tulio didn't design a long cage NR and the derailleur is going to catastrophically and spectacularly fail, diving into my newly built Torelli Master/Campy Record wheel, bending the hanger on my freshly painted bicycle and causing me to have to walk home in tears in my non vintage cleated shoes (the last time I had a un-repairable tire failure I walked back to my car in socks).
So far it works too well. There has to be a reason no one else has done this, other than offending The Gods of Vintage Lightweight, or, you all are capable of riding up big hills in a 42-24...
Ann Phillips, Decatur GA - home of the Franken-derailleur.