This is 81 hands in to a long HU match. I would classify the villain as loose/aggressive, but as the match went on, he started to mellow out some. He's opening ~50% of BTNs and C-betting ~50% of flops.

Full Tilt Poker $11 + $0.50 Heads Up No Limit Hold'em Tournament - t15/t30 Blinds - 2 players
The Official 2+2 Hand Converter Powered By DeucesCracked.com

Hero (BB): t1290 43 BBs
BTN/SB: t1710 57 BBs

Pre Flop: (t45) Hero is BB with 9 A
BTN/SB raises to t90, Hero calls t60

Flop: (t180) K 7 4 (2 players)
Hero checks, BTN/SB checks

Turn: (t180) 8 (2 players)
Hero checks, BTN/SB bets t90, Hero calls t90

River: (t360) 8 (2 players)
Hero checks, BTN/SB bets t270, Hero calls t270

I'm not yet sure what his range is for C-betting versus failing to C-bet, but so far, every time he's failed to C-bet the flop, he's C-bet the turn. Here are two example hands.

12 hands in:
Full Tilt Poker $11 + $0.50 Heads Up No Limit Hold'em Tournament - t15/t30 Blinds - 2 players
The Official 2+2 Hand Converter Powered By DeucesCracked.com

BTN/SB: t1845 61.50 BBs
Hero (BB): t1155 38.50 BBs

Pre Flop: (t45) Hero is BB with 6 A
BTN/SB raises to t90, Hero calls t60

Flop: (t180) K 6 8 (2 players)
Hero checks, BTN/SB checks

Turn: (t180) 9 (2 players)
Hero checks, BTN/SB bets t120, Hero calls t120

River: (t420) 9 (2 players)
Hero checks, BTN/SB bets t270, Hero folds

14 hands in:
Full Tilt Poker $11 + $0.50 Heads Up No Limit Hold'em Tournament - t20/t40 Blinds - 2 players
The Official 2+2 Hand Converter Powered By DeucesCracked.com

BTN/SB: t1875 46.88 BBs
Hero (BB): t1125 28.12 BBs

Pre Flop: (t60) Hero is BB with J K
BTN/SB raises to t120, Hero calls t80

Flop: (t240) 6 7 4 (2 players)
Hero checks, BTN/SB checks

Turn: (t240) 3 (2 players)
Hero checks, BTN/SB bets t160, Hero folds

Especially given the A6 hand, I think his range for betting the river is likely to be polarized to 8x or air as I think his high C-bet% indicates that he's probably betting all his Kx 7x hands, and if his checking back flop range includes big 2-pair hands like K7 or K4, he might not bet them on this river. Therefore I should call.

What are your thoughts on my ideas about his range? Is this a river call?

1) I fold the turn sir, I know he looks fos but there are tons of draws that have better equity and we have a hard time on alot of rivers if he decides to bet again, the pairing in your case in about the best possible example.

2) An option could be to lead the dry flop. Calling turn but folding river w/ a pair is pretty bad vs calling with a bare Ax in hand 1.

In both cases, (not rly sure what hands you want nfo on ) I fold the river without laser reads, there are better ways to exploit people than Hero calls.