With a 22-250, a 24" would be better. With a sporter weight tube you won't notice any real difference in weight and you'll get more velocity. About the twist, if it's 14" I wouldn't worry about it. A lot of people spend a lot of worry trying to predict what'll shoot and what won't. Several years ago on another board some guy swore up and down that a 14 twist 22-250 absolutely wouldn't shoot plastic tipped 55's. Maybe his wouldn't, or maybe he just wasn't using the right combination. I mostly shoot 50's in .22 caliber but 55gr plastic tipped bullets have done very well in a couple .223's.
The longest 55 is a BlitzKing at .820". Next is VMax at .815", then BallisticTip at .801".
Years ago I shot a bunch of prototype factory .223 loaded with 55gr. BlitzKing through a .223 Shilen barrel with 14" twist. They were loaded to factory .223 velocity and did about 1/2"groups, maybe a little less. This was loaded to factory specs with bullets seated deep, lots of bullet jump. This stuff worked fine and killed a whole slew of groundsquirrels.
Through that same Shilen 14 twist barrel, the 55BlitzKing with VV135 powder shoots a little ragged hole at 3628 which is below 22-250 velocity. But change to VV133 powder and although max velocity is higher, best accuracy is now down at 3430 which is way below 22-250 velocity. Powder can make a big difference.
A different 223 with 14" twist barrel.....VV135 and 55Bal Tip, accuracy is at 3560 and about 3650.....again this is below 22-250 velocity.
If you'd feel more confident with a 12" twist then choose that. But if what you're getting comes in 14" twist you should be fine. You can drive yourself nuts trying to interpolate and predict how your gun will shoot with one thing or another. The only way to see what'll work is to try different combinations and find out. If your gun doesn't shoot a particular bullet very well, it's not necessarily the twist rate.....it could be the barrel just doesn't like that particular bullet. Or, maybe that powder doesn't work well with that bullet in that barrel/chamber. So try a different powder. You never know about this stuff.