I think you may have uncovered both the charm and the curse of Synchro. Because it was designed to more or less retrofit a variety of derailleurs and FWs if one is willing to play with it I think you could make it work with most anything.
I wanted to tinker with it last summer but I could not get the shifters to fit the frame I wanted them on. I thought Campi or someone had made a shifter boss milling tool but I could never find a reference to one anywhere.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk