Jerry, Many of the 650-wheeled bikes of the 40/50s in France used cantilevers of one type or another..mostly with brazed-on bosses. However I have a couple of or so bikes of that era with a bolt-on type cantilever / centre-pull brake, that came in both steel and alloy varieties. Somewhere I have a couple of Meca-Dural bikes fully equipped and will check out the brakes on these machines.
However as for brands of brakes, you could try LAM and CLB..certainly CLB did a 650-wheel version of their ALP/CLB racing brake. I suppose it was in the later 50s/early 60s when MAFAC introduced the Raid model for 650 wheels.
Hope this helps in some way..but there are more brands out there..
Norris Lockley, now back in Settle UK (very unfortunately)