I have lots of other guns that are capable of taking elk but nothing that I'm capable of making those 350+ yard kill shots with.
A 308 is a legitimate 400 yard elk gun, a 30-06 is more than capable at 500, your 300 WBY is a 600 yard gun. IF you are good enough to shoot them at those ranges
If you are going to limit your shots to 350 yards I'd go 308 or 30-06 and not look back.
It is smaller than I'd like, but don't tell this girl a 243 isn't enough for an elk gun.