Chuck,
Campagnolo actually made quite a few variants of covered gear cable housing. I sold a few Gran Turismo gear sets that came complete with derailleur, lever and cable in covered gear cable housing.
This is part part 605 in Campagnolo catalogues that are described as being: covered cable housing for frame mounted gear shift (105 cm)
There were also part 607 which is described as: covered cable housing for frame mounted gear shift (59 cm)
Lastly, there are part numbers 146 and 219 which are also covered cable housing for handlebar mounted shift levers in respectively 185 cm and 140 cm lengths
Having said that, I have never seen anything but low end bikes with the covered derailleur cable housing, so it would strike me as odd to see a bike of the quality of Kevin's bike with such cable housing in its original build.
Steven Maasland
Moorestown, NJ