$100 NL Bet sizing with middle set

[Poker monkey]

I want to get paid off nicely but I don't want him to fold on me. Comments on bet sizing throughout this hand please. What sizing gives the highest expectation (chance of calling x bet size) given his range?

I've only seen him for 30 hands or something, but UTG+1 is 55/8/0.5 from my limited sample.

I have $79.70 behind on the river and he covers.

BB raiser is 26/13/1.3

No Limit Holdem Ring game
Blinds: $0.50/$1
9 players
Converter

Stack sizes:
UTG: $106.75
UTG+1: $181
MP1: $240.15
MP2: $99.35
Hero: $119.70
CO: $100
Button: $100
SB: $71.70
BB: $418.60

Pre-flop: (9 players) Hero is MP3 with 7[img]/images/graemlins/heart.gif[/img] 7[img]/images/graemlins/club.gif[/img]
UTG folds, UTG+1 calls, 2 folds, Hero calls, 2 folds, SB calls, <font color="#cc0000">BB raises to $5</font>, UTG+1 calls, Hero calls, SB folds.

Flop: 4[img]/images/graemlins/heart.gif[/img] 7[img]/images/graemlins/diamond.gif[/img] K[img]/images/graemlins/diamond.gif[/img] ($16, 3 players)
BB checks, <font color="#cc0000">UTG+1 bets $1</font>, <font color="#cc0000">Hero raises to $10</font>, BB folds, UTG+1 calls.

Turn: 2[img]/images/graemlins/club.gif[/img] ($36, 2 players)
UTG+1 checks, <font color="#cc0000">Hero bets $25</font>, UTG+1 calls.

River: 3[img]/images/graemlins/heart.gif[/img] ($86, 2 players)
UTG+1 checks, <font color="#cc0000">Hero bets $50</font>