I haven't had one in a TC, but have had 3 of "the original 221 Fireballs," the XP-100's. They initially came out with a 1:14" twist, then with the advent of the XP-100R, they updated to a 1:12" twist, both of which were aimed at shooting 35-50grn bullets, and the change being driven by the fact the 1:14" didn't run the 50's all so well.
You should be able to kick up over 2550fps with the 55grn pills in a 12" TC. You'd do fine with a 1:10" if you only ever shot the 55 FMJ's at that speed, but the tipped bullets are too long to be stabilized by the 1:10", I'd personally go with a 1:9" if I were planning 0-200yrd shooting, 1:8" if I were planning any farther. The 55 V-max needs a 1:9" to stabilize "confidently" according to Berger's stability simulator, and is on the ragged edge with a 1:10". The 55TTSX assuredly needs a 1:9" to stabilize, as I'd assume any of the other tipped monometals would.
Otherwise, remind yourself the 221 Fireball was never meant to be a "baby 223rem." It was designed to shoot the lighter 22cal pills, and it does so very well. If I were going to plan a longer range 221 Fireball barrel, I'd be hard pressed to talk myself out of a 1:7" twist barrel, crowned at 14", throated for the 69 SMK - it's hard for me to remind myself "it's not a baby 223rem" too. Reason would win out and I'd go back to a standard 1:12" with a 40grn Blitzking, which is why I haven't ever rebarreled my 221FB XP100's.