It's early in a deep stack 200 person MTT. I'm in the cutoff with 13,000, villain is effective stack (on the button) with 11,500. No real read yet. Blinds are 50/100.

It's folded round. I have 7h5h and raise to 300, he flats and the blinds move out the way.

Flop comes 4s6s8s and I make a standard 2/3 pot raise and he calls.
Turn is 10s, we both check.
River is 2c, we both check and he turns over 7s7c.

Should I be looking to take a more aggressive line here. Is it likely I could move someone I don't really know off a weak flush early in a tournament or is this just too risky?

There are some hands he can call flop with that have no spade. Ok not loads but given as played it goes check check on turn we do have some sdv when we get to river.
I don't like barreling turn and river against an unknown ( buy in and where this tournament would help indicate player pool tendencies).

Obviously given actual holding barraling would of been very +EV but we don't know if he would hero call with Qs given that he can defend on the button vs a late pos raiser fairly wide he can have all sorts of broadway combos and if he does call all the way with Qs+ then we have a fair few calling combos. When this is combined with what sdv we do have I don't like 3 barrals here.

Until recently I only played mttsng so am not that used to playing 115bb deep. So am not used to spots where I could 3 barrel and still have a usable stack behind. so you may get a different and therefore better qualified opinion on the MTT forum as they are used to this effective stack sizing.

Actually having thought about it I agree that I should never really bluff here given I have good showdown value. As you say he's never folding Qs+ and sometimes won't fold 7/8/9/10/Js as well. That's a lot of cards that he could easily have and would lose me a lot of chips. It's just a frustrating spot to flop a straight and know you're often not good on the turn.

If you had total air here, then a river bet would make sense. But with some showdown value id just check back. Though depending on the villain I may take a different approach and bet out small on the river to get lower value hands to continue and fold to raises(this is particularly true if I'm going to call a bet)