As mentioned earlier IMR 7828 SC will work well. There's six or seven of us with 22-250 AI s and 7828 and H1000 have been great powders for years. We re shooting 8 twist with 75 s and 80 s. Around 42-43 of 7828 with the 75 has given 3400-3450. Charge dependent on rifle. H1000 takes another grain or so... work up though as these are full tilt loads.
Believe it or not I ve had great luck with IMR4831, 39-39.5 grs with 80 gr Berger VLD. Right at 3400 fps in my 26" barrel and half inch MOA. Have quite a bit of this powder and pleasantly surprised when I tried it! Again, work up as it's full pressure and Bergers have shorter bearing surface than most other bullets.
We found R26 to work good but no better accuracy wise than the other mentioned powders, around 50 fps more but due to it being so hard to find we ll all continue with our 7828, H1000 and me with my ZiMR4831.
Good Luck, the 22-250 AI is a good one. Now that the 22 Creed has brass that ll be a much easy proposition though.