Worst Part of this Line?

[KStV]

$1 + $0.25 45-player SnG (Full Tilt). Blinds t20/t40.

Typical table at these stakes, but no read on BB.

Hero (t1,630)
BB (t1,260)

5 folds.
Hero is in the CO with 7 [img]/images/graemlins/club.gif[/img] 7 [img]/images/graemlins/heart.gif[/img] and raises to t150.
Button and SB fold.
BB calls.

Pot = t320

FLOP: A [img]/images/graemlins/club.gif[/img] 7 [img]/images/graemlins/diamond.gif[/img] J [img]/images/graemlins/club.gif[/img]

BB checks. Hero checks behind.

TURN: 4 [img]/images/graemlins/club.gif[/img]

BB bets t40. CO raises to t300. BB calls.

Pot= t920

RIVER: 6 [img]/images/graemlins/club.gif[/img] [A [img]/images/graemlins/club.gif[/img] 7 [img]/images/graemlins/diamond.gif[/img] J [img]/images/graemlins/club.gif[/img] 4 [img]/images/graemlins/club.gif[/img] 6 [img]/images/graemlins/club.gif[/img]]

BB bets t500
Hero?