villain is basically unknown, but hes been around a couple orbits, and enough for me to tell hes a fish, just not enough to tell how big a fish he is. so is this just a flat, or shove?

PokerStars No-Limit Hold'em, $2 BB (6 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Button ($332.45)
SB ($197.30)
BB ($203)
UTG ($281.25)
MP ($254.85)
Hero ($239.05)

Preflop: Hero is CO with J, K.
2 folds, Hero raises to $6, 1 fold, SB calls $5, 1 fold.

Flop: ($14) 4, 8, 7 (2 players)
SB checks, Hero checks.

Turn: ($14) K (2 players)
SB checks, Hero bets $10, SB raises to $20, Hero calls $10.

River: ($54) J (2 players)
SB bets $48, hero...