What's the turn play? AT in SB

[tipperdog]

Early in live tourney. We start with T2,500. Start of second level. I have ~2,200. Cutoff this hand is a huge stack, ~7,000 (doubled up with AA twice). Blinds were just raised to 25/50. I am SB with ATo.

Fold to the cutoff who "calls" T25. The dealer tells him the blind has been raised and he must add another T25, which he does reluctantly. Fold to me and I raise to T175. BB folds and cutoff calls.

The flop comes 378 rainbow. I bet T400 and cutoff calls quickly. The turn is a 9, completing the rainbow, and giving me a one-card open-end straight draw and two overcards. I have ~T1,700 left.

What's the play (and feel free to critique anything else, of course)?