NLTRN $100 - Second pair vs good (aggressive) regular

[Conspiracy]

Villain is a good regular I usually try not to play against. He is a bit too aggressive but that makes him hard to play.

pre, flop and turn is standard imo but river is a bit tricky given how aggro he is.

Heads up $100 NL (Real/Tournament)
Seat 1: Hero (1180.00)
Seat 2: Villain (1820.00)
Hero post SB 25.00
Villain post BB 50.00
** Deal **
Hero [K[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/diamond.gif[/img]]
Villain [N/A, N/A]
*** Bet Round 1 ***
Hero Raise to 125.00
Villain Call 125.00
*** Flop(Board): *** : [8[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/club.gif[/img]]
*** Bet Round 2 ***
Villain Check
Hero Bet 150.00
Villain Call 150.00
*** Turn(Board): *** : [8[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/club.gif[/img], A[img]/images/graemlins/heart.gif[/img]]
*** Bet Round 3 ***
Villain Check
Hero Check
*** River(Board): *** : [8[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/club.gif[/img], A[img]/images/graemlins/heart.gif[/img], 5[img]/images/graemlins/spade.gif[/img]]
*** Bet Round 4 ***
Villain Bet 300.00
Hero ???