If you are talking about a true long range elk rifle then IMHO none of the ones you listed will qualify and you won't find a rifle on the average gun shops shelf that would be capable of doing it either.

If you are talking at least 600 yards and being able to kill an elk with a single well placed shot then the cartridge needs to be able to fire a mid to heavy for caliber, very streamlinedbullet at 3000 fps or faster and this would be a hand loading proposition only. The rifle would be custom built and capable of .5moa. Then would come countless hours at the range shooting from various different field positions.

My list would include large capacity 30 and 338 cartridges. Just a few that would be on my short list.....

300RUM - will fire at 180 grain bullet at 3300 fps and a 210 grain Berger at 3100+
30-378WBY mag. - Will fire the same bullets about150-200 fps faster.
7.82 Warbird - About the same ballistics as the 30-378.

338RUM - Will fire a 250 grain bullet at 3000 fps and a 225 at 3100+ from a 26" barrel.
338-378WBY mag - Same bullets about 100fps faster.
8.59 Titan - About the same ballistics as the 338-378.