Early in tourney facing a huge overbet of pot

[foobar]

Hey all,

Early in $10 Stars MTT...all stacks ~1500...blinds 10/20...no reads.

I have A3h in MP. 2 limpers in front and I limp along. Couple more limpers, 6 to the flop, which comes:

4h 5c 7h

Check to EP who overbets the pot for about T500. What's your play here? I figured my flush and ace outs were definitely good...but wasn't positive if I'd be happy about seeing a non-heart 6.

Anyhow, I think the play is pretty clearcut in a cash game, but I'm not so sure about the correct move early in tourney. All thoughts appreciated.