I too use NOS asbestos brakes. None of the modern materials is as good. The 'Holy Grail' of the brake industry after so many years remains to find a material as all round ideal as a braking medium. If you are worried about the infinitesimal risk from the dust, when you change or adjust them, wear a paper mask and just wash down the shoes and mechanisms into a basin with brake cleaner. The issue as brake shops was mechanics blowing off the dust day in, day out with airlines filling the shop with a persistent fog of brake dust.