Some of the repro Mafac pads are quite dangerous - I had one "melt" under hard braking (on a cantilever), causing the pad dive under the rim... Fortunately, I was able to stop anyhow. A friend had the same experience.
Since then, I stick with genuine Mafac pads (letters MAFAC on the pad), with no problems.
BTW, all Mafac centerpulls can be used with brazed-on pivots, bronze or plastic bushings. In fact, many Alex Singers use plastic-bushing Racers, nicely polished, of course. Both types brake just fine, too. Maybe the bronze bushings last longer?
Jan Heine, Seattle