Most modern centre pull calipers don't require special bosses, they come in direct mount (special bosses), allen key (like most other calipers) or nut n bolt (like calipers from when I were a lad).
Yeah, but AIUI you get much less flex if direct-mounted? I could possibly be tempted by something like the Compass centrepulls, but at £200 per brake my rational brain tells me they'd have to be significantly better than cantis.
True, but if you're having a custom frame then the mounts could be added from the off, Dia Compe do a nice one, for less then Compass/Rene Herse, and the Paul ones are reportedly quite stiff/beefy, but quite spendy.
Most modern centre pull calipers don't require special bosses, they come in direct mount (special bosses), allen key (like most other calipers) or nut n bolt (like calipers from when I were a lad).