I have hunted that area [12] near Trappers Lake. Cool area.... I would use the 257 esp. if you are more comfortable with it.
Out of the 7 elk I have killed the closest was 15 yards and the longest was 120, but I always hunt in the timber and get bored sitting around on "Meadow watch". It is amazing how in the last 50 years elk have gotten so much tougher and need a 300 plus magnum to kill them when they used to be able to die from a '06, 270, 300 Sav., 35 rem. etc.