Interesting HU hand, top 2 on non-threatening board NLCASH, $200

[MasterLJ]

Villain is fairly weak passive. He has not shown this much aggression on any hand previously.

Full Tilt - No Limit Hold'em HU Cash Game - $1/$2 Blinds (LegoPoker HH Converter)

Villain (BB): $193.00
Hero (BTN/SB): $398.00

Preflop: Hero is dealt K [img]/images/graemlins/spade.gif[/img] Q [img]/images/graemlins/club.gif[/img](4 Players)
Hero raises to $7.00, Villain calls $5.00

Flop: ($14) 2 [img]/images/graemlins/club.gif[/img] 5 [img]/images/graemlins/spade.gif[/img] 4 [img]/images/graemlins/spade.gif[/img] (2 Players)
BB checks, Hero checks

Turn: ($14) K [img]/images/graemlins/diamond.gif[/img] (2 Players)
SB bets $14, Hero calls $14

River: ($42) Q [img]/images/graemlins/heart.gif[/img] (2 Players)
SB bets $42, Hero --- ??? - Call or Raise

I usually C-bet that flop, but I've been beating him to death with aggression and decided to switch gears to tone it down to give me credit for some bluffs later on.

Obviously I'm at least calling that river... is there any value in shoving? What worse hands call?