Easy river value raise?

[w_alloy]

My first time playing NL200 (starting low after a recent downswing/break), so I'm not too familiar with the game.

I am not too impressed with villian's play, but he seems better than most of these 1/2 donks. He is multitabling, and in the ~200 hands we have played together, I have 3 bet him 2 or 3 times and he has folded preflop each. He is running at about 30/20 with 1.4 AF. My image is reasonably aggressive and tricky, but who knows how close attention he is paying.

PokerStars No-Limit Hold'em, $2 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

SB ($126.75)
BB ($32.45)
UTG ($192.85)
MP ($211.75)
CO ($972.25)
Hero ($399)

Preflop: Hero is Button with 8[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/spade.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">MP raises to $8</font>, <font color="#666666">1 fold</font>, <font color="#CC3333">Hero raises to $24</font>, <font color="#666666">2 folds</font>, MP calls $16.

Flop: ($51) K[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/spade.gif[/img], 8[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
MP checks, Hero checks.

Turn: ($51) 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
MP checks, Hero checks.

River: ($51) 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">MP bets $40</font>

Thoughts: I don't bet flop because it seems unlikely he calls with worse, and I don't want him to raise and I have to fold to a possible bluff. Turn same thing. River I get hit, and he makes a strong lead, and I am obviously ahead of his range... But I am unsure if he will call with enough worse hands for me to raise, and stack sizes mean the raise has to be large (about 1.2 pots).