Did someone write that Campagnolo brake inserts fit the Mafac pad holders? No, Dura Ace 7400. My mistake.
Classic Bikes has Scott/Mathauser Campagnolo replacement inserts just in case they do fit.
Kool Stop Continentals for threaded posts may work (Tigers only?). I used the also-mentioned Mathauser pads in canti-post for my 2000s, and it stopped the squeal, but only with toe-in. Wet weather sometimes brings it back for brief periods.
Before the adjustment, the hard-braking warning squeal for errant pedestrians was indeed especially useful by,
Ray Coffey
in Boston, Mass. - birthplace of Jay Walker