[damedley]

The first thing that is confusing to me is you start with 100BB stacks and then say he raised 40. Presumably that's not 40 BB! :-) Looks like since the pot is 310 on the flop the BB is 20. The second thing that is confusing is you say he raised 40 then you raised TO 140. Is the difference intentional (i.e., he raised TO 60)? It makes a big difference to me what his initial raise was. If it was only 2xBB then that's totally weird and changes the complexion of the hand.

Presuming he raised TO 60, I think you check behind here versus competent opponents. Seems like a pretty clear case of a medium-strength hand that isn't going to get a lot of calls from worse hands. If you check behind on the turn you can play the river for just one bet. Considering he open-raised from the CO he could have just about anything. While his check/call on the flop suggests two big cards to me a 6 or 78 is not out of the question. You're giving up some bets against TT and JJ but saving bets against KK and AA, so that's a wash imo.