I've used a lot of US869 in other calibers and I'm probably one of the few that actually likes it but something I've learned with using it is if I'm not seating bullets close or on the lands, it will give me some pretty crazy extreme spreads but if I load on or close to the lands it's a whole different story. I mostly shoot Berger bullets which typically shoot best when they are seated close or touching so the two work for me but if I couldn't seat them close to touching I'd probably look for a different powder to use than US869.
RL33 and Vihtavuori N570 would both be good powder choices as well and like was already mentioned, with as much horsepower the 26 Nosler has, the new 155 Berger and other heavy for caliber bullets like it, should work well with this setup. Provided you have a barrel with enough twist to stabilize them.