Hero KK26s hijack with 700 stack.

Hero limps to 5, and BTN who is a LAG who plays 70-80% hands pre raises to 20. 3 more callers and hero completes.

Flop: JJTr all x to BTN who x behind aswell.
Turn: 2 thats bring in a fd, everybody x to hero who bets 60 into 100 and LAG calls(has hero covered), rest folds.
River: 6 that completes bd flush, hero x, LAG bets 150 into 220 hero goes all in.

Allright some background info on the lag and how the views me. He plays ANYTHING preflop but is pretty decent postflop. HE CAN FOLD if he thinks he is beat as I have seen it happen several times. He views hero as a super nit who only plays the nuts basicly. Although he has seen me bluff with ''smaller'' sizings on one ocassion. There I suspect he could have floated me here or called pretty wide.

My plan was to x/c any brick rivers. When the fd comes in I dont think he will fold if I bet out but should find a fold with a flush if I x/r. Do you guys think a nitty player as me could have checked back JTxx on the flp then bet small to get value and x hoping a flush that hits bets? Anyway anything on my line/thought process is nice to get feedback on :).