Not sure if it's widely known: Mafac Tandem canti is 2 mm taller than the short-arm Criterium canti. So ideally, for Tandem brakes, the posts should have been put on 2 mm lower, for the pads to hit the rim just right. So if you're putting 700c in a bike made for 27" (unlikely in this case but it happens...), then Criterium brakes will fit better than Tandem. 2 mm is a noticeable amount, but Mafacs can usually adjust that much by the "nod" angle adjustment of the pads. It's not a true up/down translation adjustment, but as long as the angle you adjust them through is small, using angle as a height fine-adjust is OK. It's just in the edge cases, like where the posts are too high b/c they're for 27", that the extra 2 mm on Tandem arms can be a deal-breaker.
The lack of any up/down adjustment is just about the only thing I don't like about Mafac cantis. When the posts are at just the right height, I rank them up there with the best modern rim brakes.