With a 14 twist 22-250, you will be limited to shooting light bullets ~40-45 grains (read low BC). They'll be screaming fast, but won't be very stable when shooting long range.
I have a 12 twist 223. It will shoot 55-60 grain bullets (read: better BC). While not as fast as a 22-250, it will be more stable and potentially more accurate at longer range. My 12 twist 223 will shoot 600 yards, but not quite 'yote accurate at that range.
If I were to build a long range 22, I'd want a 7 or 8 twist so I could shoot 90+ grain bullets. Then you have a 1k rifle with either the 223 or 22-250.
Here's an interesting article for you.... http://www.longrangehunting.com/arti...223-mile-1.php
Your mileage may vary.