Short answer, bet/fold. you played it fine.

I think this is a tough flop spot to play without reads. Vs maniacs it's an easy bet/gii spot, vs nits it's probably best to 2/3 pot  fold to a x/pot , and readless I like both.

Merits to both imo, betting builds a pot which is good considering you have a ton of equity vs a typical check/calling range and there are a lot of good turns for you. 

checking back it good too, because when you turn a flush your hand is under-repped and you may get two streets of value vs a smaller flush or vs a straight. You can also turn a 9 which is a good card, giving you a wrap+flushdraw. A 7 can be a good card as well, not to mention a Ten or Ace isn't that bad either. 

The problem with checking here, is you don't give your self a chance to pick up the pot now, and you have no idea how much equity you have vs your opponents x/r range because your readless. Not to mention, there are a lot of turns that you hate, like a 6 5 4 or Q. The fact that your actual hand is only a pair of 7's, is enough for me to favor betting over checking here.

Betting and checking back are both fine when we're readless.  This is a board that sort of hits SB's calling range but might not smack it, so I don't expect tons of immediate fold, nor x/r.

As played it's kinda ugly.  When readless, I'd assign him a range of {2p (mostly Q7/Q6), sets, pair + wrap, pair + good FD} or something similar to that.  Against this range we don't have tons of implied odds when hitting a flush ott (esp when it's not the nut flush), but we might be able to bluff on some turn cards if he checks to us.  That said I don't think peeling is horrible, and it's probably close to bet/folding imo.