Bet sizing on 4-straight board, i has a straight

[reup]

Villain's kind of strange his stats are 25/14/1.85 ~485 hands. We've been at the table for over 300 hands at this point. I've been playing aggressively 30/27/6 and playing one table while he's playing five or six. Over the first hundred hands he was playing very tag fishy and I either cbet him relentlessly, or checked behind in position on the turn and bet at scare cards like an ace on the river, winning most or all of our first confrontations. he built his stack by playing pretty standard and having some dude shove second pair into him in a threebet pot while he had an acequeen on an A92 flop. About three hands ago he c/r me for the first time when i cbet a flop of 8[img]/images/graemlins/diamond.gif[/img]4[img]/images/graemlins/diamond.gif[/img]2[img]/images/graemlins/spade.gif[/img] holding 7[img]/images/graemlins/diamond.gif[/img]9[img]/images/graemlins/diamond.gif[/img], he c/r from the sb, smallish, a little over a minraise, i call he bets big on the turn blank and i folded meh i really didn't know what to do i wasn't priced in though maybe with implied odds but that was pretty much the first time he played back at me in three hundred hands so I gave him credit for a set or two pair since he plays pretty standard and on the passive side for sure. Weaktight was my initial read on him.

Full Tilt Poker - No Limit Hold'em Cash Game - $2/$4 Blinds - 6 Players - (LegoPoker Hand History Converter)

SB: $410.60
BB: $520.40
UTG: $120.00
Hero (MP): $545.90
CO: $605.60
BTN: $751.60

UTG posts $4.00
Preflop: Hero is dealt 9[img]/images/graemlins/diamond.gif[/img] 9[img]/images/graemlins/heart.gif[/img] (6 Players)
UTG checks, <font color="red">Hero raises to $18.00</font>, CO folds, BTN calls $18.00, 3 folds

Flop: ($46) 6[img]/images/graemlins/diamond.gif[/img] 7[img]/images/graemlins/club.gif[/img] 8[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">Hero bets $34.00</font>, BTN calls $34.00

Turn: ($114) 5[img]/images/graemlins/diamond.gif[/img] (2 Players)
<font color="red">Hero bets $67.00</font>, BTN calls $67.00

River: ($248) A[img]/images/graemlins/diamond.gif[/img] (2 Players)
<font color="red">Hero bets $122.00</font>...

my bets kinda morphed into halfpottish bets, too small? after he calls my turn bet what do you think he has and how much would you bet on the river since we can def. narrow his range at this point.