Thanks all. The pads that are on there now are postless, using a bolt at the center of the pad with some very specific washers instead. But I don't see why a threaded post and nut wouldn't work. I may just have to try the KS Eagle options. The only problem with the current cantilevers is that the springs are really strong, requiring quite a bit of strength to squeeze. It's also a slightly too long reach from grip to lever for her. But if I go for new v-brakes and levers, I'll need to replace the integrated shifters too, making sure they work with the old derailleurs... I think I'll try the not-quite-perfect pads first, see how it goes!

Thanks,
Don