In the last rifle we did, we were running 69.0 grains of IMR 7828, Remington 9 1/2 large rifle magnum primer, Weatherby brass, and a C.O.L of 3.290". This was yielding velocity well over 3300 FPS from a 26" Hart barrel, and averaging aroun .3" groups at 100 yards. I use a match dimension chamber reamer with a shorter throat than a factory chamber has, and in our chambers that seating depth is .105" from touching the lands. I've tried seating them closer to that in our chambers, and they haven't shot as well.
This is in a different direction, but I've also had good results with the Sierra 117 grain Gameking BTSP in this caliber. Here is my pet load for that bullet:
Wby brass
65.0 gr H4831SC
Rem 9 1/2 primer
3.295" C.O.L. (.005" from land in our chambers)
3291 FPS
Best group with that load was .166" in a Douglas 26" barrel. Hope this helps, and Happy Shooting!