^^^
What he said, practice shooting and you'll start to figure out what you want. 6.5 and 7mm cartridges can get you out those distances fairly easy, and depending if your building on a long or short action will help determine your cartridge.
Another question is if you're going to reload your own ammunition or just purchase factory cartridges, because that'll also narrow down your options.
IMHO I would look at the 6.5-284, 260, 6.5x47, 6.5 Creedmore and wouldn't count out a plain Jane 243. But there are plenty of cartridges that'll meet your needs