I couldn`t help myself 3-barrel bluffing this guy

[MATT111]

2/4 NLHE
I have 818$, TAG villain covers. The table just got HU. We don`t have any history together and I don`t think he has much of a read on me except that I`m a TAG.
I obviously could check behind on the flop or turn hoping I improve but put him on a hand that couldn`t stand a lot more pressure. After he called the turn AK is probably his most likely hand, maybe a stubborn AQ.
Should we follow through on the river or are we giving up?

Preflop
Hero is otb/SB with 7 [img]/images/graemlins/heart.gif[/img] 8 [img]/images/graemlins/heart.gif[/img]
Hero raises to 12, villain reraises to 50

Flop (100$)
Q [img]/images/graemlins/club.gif[/img] 8 [img]/images/graemlins/spade.gif[/img] K [img]/images/graemlins/diamond.gif[/img]

Villain checks, Hero bets 77, Villain calls

Turn (254$)
2 [img]/images/graemlins/heart.gif[/img]

Villain checks, Hero bets 179, Villain calls.

River (614$)
3[img]/images/graemlins/heart.gif[/img]

Villain checks, Hero has 508 left to shove