We rode a version of that frame from 1973 to 1975, only with Mixte in the rear. We rode it a lot before we replaced it a Bob Jackson tandem. I hope your frame is stiffer than ours was. We used to call it the "articulating bike" because the frame would flex so much when we stood. Like yours, our frame had Mafac cantilever brakes and came with 27" wheels. We were able to adjust the brakes so that we could ride on sew-up rims, which have the same effective diameter as a 700c rim.