villain is 50/15.6/1.0 over 35 hands, unknown. i'm wondering how much i should value bet on the river to get call from worse hands given his stats.

PokerStars No-Limit Hold'em, $1.00 BB (9 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

UTG+1 ($100.80)
Hero ($119.50)
MP2 ($107.75)
MP3 ($18.50)
CO ($25.30)
Button ($81.15)
SB ($349.50)
BB ($168.10)
UTG ($90.15)

Preflop: Hero is MP1 with 8, 8.
2 folds, Hero raises to $4, MP2 calls $4, 2 folds, Button calls $4, SB calls $3.50, 1 fold.

Flop: ($17) 4, 6, 2 (4 players)
SB checks, Hero bets $12, MP2 folds, Button folds, SB calls $12.

Turn: ($41) 8 (2 players)
SB checks, Hero bets $28, SB calls $28.

River: ($97) T (2 players)
SB checks, [color=#CC3333]Hero bets ? how much?