Look at the 6XC. You'll love the barrel life and it will do what you want. Elk would be all about shot placement. One of my barrels has almost 3200 rounds thru it and is still shooting very small groups and hasn't lost much speed. 26" shooting 108 ELDM at 2980.
Yup,. 6 XC with 1-7.5 to 1-8 Twist, is your best, all around 6 MM choice, with better barrel life than either the 6 Creed or, .243 !
Very accurate, for use on, Coyotes to Deer / Antelope with, 70, 80, or, 95 gr Bullets for Yotes and, the 108 grain, Elite Hunter Bergers for,..
the Bigger Game.
Your .270 WSM with 140 gr. Berger Classic's at, 3,200 FPS is, very GOOD "Medicine" for Elk to,.. 700- 800 Yards. ( I Like Mine, a LOT !!! )
You'd be "Covered" with, those Two !
You could "Get by" for Short Range Elk with, a 6.5 Creedmoor, using 140 gr. Berger Elite Hunt's or, 143 gr. ELD-X's ( Maybe, 400 - 500 yds MAX ).
And, use, the 123 or 130 gr. ELD-M's for,.. Yotes !
I HAVE, all 3 cartridges / Rifles, in my safe for,.. different uses.