Yea. No reason to shy away from a 9" twist. Anything down to 75 Gr VMaxes would be fine.
And I really hate that I'm saying this....because the 250 and 250 AI are two of my favorites, and I have dies for both and brass for both and I'm still working on finishing a 250 AI (long journey, long story).
But if I didn't have brass or dies already, I'd go with a 25 Creedmoor chamber. Alpha brass is excellent, or plenty of 6mm and 6.5mm brass to neck up or down a little. I haven't checked die costs, so don't know about that.
