RE: heavies in a 22-250?
Going up to 80s I would not go less than a 9 twist. The 22-250 I have has a 30 inch tube and gets the speed up there pretty good though I don't recall exactly. If I cannot blow up a 52 in a 6.5 twist at 3300 fps, I suspect a 9 or 8 twist will both be fine in 22250ai.
But take the route you choose. I only offer what I have experienced. Just as additional info.