The pre-WWII Schneider Angulon 210mm f:6.8 has an image circle of 500mm, and converts to 330mm f:12 (rear) and 450mm f:14 (front). It's about as sharp when converted as half a Dagor - usable in a pinch, but not as good as a whole lens.

Zeiss made the Serie VII convertible Doppelprotar elements in focal lengths wgich included 41, 48, 59 and 69cm; and the somewhat cheaper Serie IV in 43, 50, 60 and 70cm. The usable image circle for each of these elements should be about equal to the focal length.

Other possibilities were the offerings from Goerz (Pantar), Steinheil (Satz Orthostigmat Serie A), Suter (Anastigmat Serie I, Serie III and Serie IIIa), Plaubel (Satz-Orthar F/6), and also others from Steinheil, Voigtländer, Busch, Staeble, Rodenstock, Meyer and so on. The main problem with these lenses is to find thae: They are rare enough in the shorter focal lengths, and get progressively rarer with increased focal length.

AND: For contact prints, there are meniscus sets of sufficient sharpness - like the Busch Vade Mecum which goes to 750mm.

Most symmetrical and nearly symmetrical lenses can be "converted" if one is willing to lose a little bit of the ultimate sharpness. This includes Plasmats, Dialytes and Aplanats (=Rapid Rectilinears). Only you can decide if the results are sharp enough.