800 is alot to open up for preflop with more limpers. 600 should have been fine. On the flop, a 1/2-3/4 pot bet is good, so around 1000 if you bet 600 preflop, since there would be about 1500 in the pot. When the turn brings a 9, theres 4 to a straight, and against a calling station like you said he is, hes not very likely to fold here, so im probly giving up on this pot and check/folding.