Spaniel - I wish you luck. If this is your first elk hunt - a few words of advice. Don't expect to see a 6x6 around every corner. They are far and few between. I've been on 3 elk hunts and haven't dropped the hammer yet. I've had opportunities on animals that didn't meet my stds (spikes - 4x4s). - Take a 4x4 if you want and don't look back. If you're in open country, take the 300. Get in shape - my last hunt I walked 5 - 15 miles every day, and I swear out of the entire 7 days I don't think 100 yds was flat. You were either going up or down. On this last hunt I saw elk every day - but always saw the really big bulls while driving in (crossing posted ground) and could never locate locate one during legal shooting hours.
Again - good luck. I hope you collect on both an elk and a nice mulie. Oh, and bear too.