The HH converter isn't working so please see below. 

No real info on villain, I only have 8 hands on him. My question is whether we should turn our hand into a blufff OTR here vs a villain who has shown strength on two streets. 

Obviously it's not ideal as we're repping specifically a 7 or QJ. But given the pot size, is a bluff here justifiable against an unknown opponent or should we always just give it up?

Thanks in advance.

PokerStars Hand #133385404701: Tournament #1188375124, $2.50+$0.25 USD Hold'em No Limit - Level XIV (800/1600) - 2015/04/08 10:10:33 AEST [2015/04/07 20:10:33 ET]
Table '1188375124 23' 9-max Seat #4 is the button
Seat 1: swindler57 (145093 in chips) 
Seat 2: IMI555 (170978 in chips) 
Seat 3: KingKong8985 (174221 in chips) 
Seat 4: Tranekjer (165648 in chips) 
Seat 5: yrp03a (44228 in chips) 
Seat 6: martu11 (33615 in chips) 
Seat 7: ambRRRR (222532 in chips) 
Seat 8: TR 2/14 (33110 in chips) 
Seat 9: le8end_25 (15736 in chips) 
swindler57: posts the ante 160
IMI555: posts the ante 160
KingKong8985: posts the ante 160
Tranekjer: posts the ante 160
yrp03a: posts the ante 160
martu11: posts the ante 160
ambRRRR: posts the ante 160
TR 2/14: posts the ante 160
le8end_25: posts the ante 160
yrp03a: posts small blind 800
martu11: posts big blind 1600
*** HOLE CARDS ***
Dealt to swindler57 [9s Ks]
Tranekjer said, "nice fold wp"
ambRRRR: folds 
TR 2/14: folds 
le8end_25: folds 
swindler57: raises 1600 to 3200
IMI555: calls 3200
KingKong8985: calls 3200
Tranekjer: folds 
yrp03a: folds 
martu11: calls 1600
*** FLOP *** [6h Tc 8s]
martu11: checks 
swindler57: bets 6990
IMI555: folds 
KingKong8985: raises 6990 to 13980
martu11: folds 
swindler57: calls 6990
*** TURN *** [6h Tc 8s] [5s]
swindler57: checks 
KingKong8985: bets 16000
swindler57: calls 16000
*** RIVER *** [6h Tc 8s 5s] [9d]
swindler57: ???