I'm sure the Diacompes 750 caliper would work well enough to stop the bike in most conditions, but consider what feels best for you and your wife to put on the bike. If aesthetics on the C&V Peugeot mixte is important enough for both of you, just bite the bullet and get a set of Mafac Racers when you find a set in good enough condition and a price you can afford. Just consider at the second caliper as a source of spare parts, to keep the other two going for the next few decades. You have to consider that they will only get more exepnsive to get them in the future.

Chombi