How do i extract maximum value from top pro in 100r?

[Bond18]

Stars 100r, villain in hand is kwob20, a tough laggy player whose played with me plenty. He is certainly capable of playing back with air on a board that looks like i whiffed.

My image is a moderately active TAG but havn't shown down garbage.

My stack: 11,900
Kwob20: 9,700

Poker Stars
No Limit Holdem Tournament
Blinds: t75/t150
9 players
Converter

Pre-flop: (9 players) Hero is MP2 with 8[img]/images/graemlins/heart.gif[/img] 8[img]/images/graemlins/club.gif[/img]
3 folds, <font color="#cc0000">Hero raises to t450</font>, MP3 folds, CO calls t450 <font color="aaaaaa">(pot was t675)</font>, 3 folds.

Flop: 3[img]/images/graemlins/heart.gif[/img] 3[img]/images/graemlins/diamond.gif[/img] 8[img]/images/graemlins/spade.gif[/img] (t1125, 2 players)
<font color="#cc0000">Hero bets t600</font>, <font color="#cc0000">CO raises to t1500</font>, Hero calls t900 <font color="aaaaaa">(pot was t3225)</font>.

Turn: K[img]/images/graemlins/diamond.gif[/img] (t4125, 2 players)
Hero checks, <font color="#cc0000">CO bets t1250</font>, Hero calls t1250 <font color="aaaaaa">(pot was t5375)</font>.

River: 4[img]/images/graemlins/diamond.gif[/img] (t6625, 2 players)
Hero?

Thoughts on my line up until this point? Whats your river play?