Hi list. I am certainly no expert on Italian frames , but I would suggest that the rear dropouts may have changed to enable the use of a direct mount deraiuler. Thirty years ago this sort of thing was frequently done to update a favorite ;or cheaply acquired but good quality,older frame . Of course the "collector " concern for originality was far in the future, and whatever the current style of dropout the LBS had in stock was generaly used. No doubt long Campy dropouts could have been tracked down but why bother when the intention was to modernize an older frame. It also might explain why the rear dropouts are forged, and the fronts appear to be stamped.