I have been waiting to hear from someone who has put a T-5 behind a 216, especially a fresh one. I recently put a T-5 behind a full pressure 235 in My '50 and am absolutely amazed how it brought this engine/truck to life! I would put the 216 in if I were you. Just think how sweet the original engine will look in the engine bay.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission