Although it's not particularly glamorous, a SunTour Cyclone front derailleur is period-appropriate (first came out in '74, I think) and I am using one on my '74 Jack Taylor with an early campy triple up front and SunTour barcons shifting a SunTour Vista V-GT Luxe in the rear... it works very well (although right now it's in a box as I wait for Tom Kellog to re-paint the Jack Taylor frame).
Duncan Granger
Lancaster, PA