Opp is pretty tight, a bit on the weak side (he has seemed to be folding to raises postflop in a lot of hands). When he called my flop bet I put him on an overpair. My image was semiloose-aggressive. Is this 3-barrelbluff too much? should I just slow down after he called my flopbet? Or is this a good oppurtinity to blast a nit out of a big pot?

Party Poker No-Limit Hold'em, $ BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

CO ($95.35)
Hero ($98.50)
SB ($85)
BB ($198.60)
UTG ($35.45)
MP ($47.75)

Preflop: Hero is Button with A, K. SB posts a blind of $0.50.
2 folds, CO raises to $5, Hero calls $5, 2 folds.

Flop: ($11.50) 7, 9, 7 (2 players)
CO checks, Hero bets $8, CO calls $8.

Turn: ($27.50) 8 (2 players)
CO checks, Hero bets $20, CO calls $20.

River: ($67.50) 3 (2 players)
CO checks, Hero bets $50, CO calls $50.

Final Pot: $167.50