"Can anyone on the list put a date to the general introduction of top tube brake cable braze-on's ?"
Bob,
This question was kicked around in the past. But it may not be in the archives. I saw Campagnolo braze-ons in the early 1960s on an original Ephgrave road machine. They're also listed in the Campy catalog for that period according to Chuck Schmidt. However the norm for most bikes was sometime in the mid-late 1970s.
Michael allison
New York, NY