River decision with 4 to str8 on board

[RikaKazak]

Curious if a half pot blocking/value bet is standard here, I fear that everyone will just say standard, but not 100% sure. Also, what do you think of my turn check?

Party Poker No-Limit Hold'em, $ Hero (6 max, 6 handed) FTR converter on zerodivide.cx

CO ($263.93)
Button ($3323.18)
SB ($365)
Hero ($387.60)
UTG ($454.08)
MP ($309)

Preflop: Hero is BB with 8[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/heart.gif[/img]. SB posts a blind of $2.
UTG calls $4, MP calls $4, <font color="#666666">1 fold</font>, Button calls $4, <font color="#666666">1 fold</font>, Hero checks.

Flop: ($18) 6[img]/images/graemlins/club.gif[/img], 8[img]/images/graemlins/heart.gif[/img], 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">Hero bets $12</font>, UTG folds, MP calls $12, Button folds.

Turn: ($42) 7[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">MP bets $30</font>, Hero calls $30.

River: ($102) 5[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $50</font>, Final Pot: $202