Congratulations on drawing the tag!
As far as cartridge, I would go with the biggest you have, preferrably 338 EDGE or bigger. Antelope are extremely large critters with heavy bone structure and can absorb lots of lead and still stay on their feet. Most antelope guides will deliver a back up shot after your initial shot just to make sure they don't make it into the heavy alder patches where they might ambush and maul you as you attempt to track them. Best of luck and remember, you don't have to outrun the antelope, you just have to outrun the guide.
Just Kidding. Pretty much any centerfire bullet to the chest will do the job.