On Italian ebay you can find an auction for two frames from the 40's or early 50's. Both frames come with the toothed dropouts for use with the seatstay lever Campagnolo gears. One is for use with the Cambio Corsa (17teeth) and the other is for use with the Campagnolo Paris-Roubaix (19 teeth). The seller is a friend of mine who has a nice little collection of his own ranging from numerous bikes from the late 1800's to the late 50's. I have bought from him in the past, as has Matt Gorski, and I don't think that it is a stretch to say that you can trust him implicitly.
Apart from helping a friend sell, I have no interest in this auction: