My personal opinion concerning the 22-250 compared to the 22-120 Ackley Improved is that the Ackley version is far superior. It has more punch than the standard version and the brass lasts a lot longer. On the twist side of things, I like the old 1 in 14 using projectiles up to 55 grainers. You can run much lower weight projectiles and crank them up to ridiculous speeds. Try the Barnes 36 grain Varmint Grenades.
I am not a fan of using heavy 224 calibre projectiles. I really can't see the point of choosing a fast twist 22-250AI and using heavy projectiles. It eliminates the fun of shooting really fast lower weight projectiles.
If you want heavier projectiles in the 70 and 90 grain weight range, my suggestion would be to go with a larger calibre like a .243 or .257.
On a side note, I have a 22-250AI and I also have a .220 Wilson Arrow. The Arrow is slightly ahead on speed and accuracy. Both are custom Mausers fitted with very heavy #7 profile 26" barrels.
Just my 2 cents worth.