Live: AK - value bet/check the river?

[Galwegian]

Villain is tricky/trappy LAG. He's a good LAG and he knows that I'm a TAG.

Live NLHE tourney - $150 buyin, blinds are 25/50, 10 players.

stacks
UTG (villain) - 8000
MP3 (hero) - 7000

preflop
Dealt to hero - A[img]/images/graemlins/club.gif[/img] K[img]/images/graemlins/heart.gif[/img]

UTG calls 50, 3 folds, hero raises to 150, 4 folds, UTG calls

pot = 375

flop
A[img]/images/graemlins/heart.gif[/img] 4[img]/images/graemlins/diamond.gif[/img] 5[img]/images/graemlins/club.gif[/img]
UTG checks, hero bets 300, UTG calls

pot = 975

turn
[A[img]/images/graemlins/heart.gif[/img] 4[img]/images/graemlins/diamond.gif[/img] 5[img]/images/graemlins/club.gif[/img]] A[img]/images/graemlins/spade.gif[/img]
UTG checks, hero bets 500, UTG calls

pot = 1975

river
[A[img]/images/graemlins/heart.gif[/img] 4[img]/images/graemlins/diamond.gif[/img] 5[img]/images/graemlins/club.gif[/img] A[img]/images/graemlins/spade.gif[/img]] 4[img]/images/graemlins/club.gif[/img]
UTG checks, hero ????