First off your preflop 3 bet is very weak.  You both have so many chips here it's important to put in a bigger preflop bet because you want to build somewhat of a pot here before the flop having  over 84BBs to where you can get a lot of money in if you hit big.

I'd raise much bigger at least 3x his size but probably more like 4-5x just because a re-raise of his 120 to 260 could induce more players in the pot left to act and if he's got a decent hand in a lower limit game he probably will call 480-600 chips.

I'd still lead out on this flop and then go from there. With his particular hand (please try not to show us) you likely just get a fold which those few hundred extra chips you could of got preflop might of been  the most value but other times if he peels a street an Ax type hand or somewhat of a draw then you can trend accordingly and if you hit an ace or king on the flop then hopefully he came along with the weaker ace which will allow you to get way more value since you boosted the pot preflop which is necessary when stacks are this deep.

i think that utg+1 is weak since he just limped and mp2 just min raises, which to me seems weak also. your 3-bet is def. to small should have been around  300-360 imo.   you said you dont like to risk to many chips, but if the raise is closer to 3x  then the pot is bigger when u take it down. and on flop i would c-bet and prolly TID, that way your not tryin to guess what he has. that flop is not to bad for you.  u have a gutshot, 2 overs and backdoor nut flush draw. with all of that being said u still won, but the more cards u let him see the more chances he gets lucky(if he had a 6).  well i hope this helps, gl to u at the tables