Villain is unknown to me. Should I've raised flop or turn?

Considering the deep effective stack size I didn't want to 3-bet the flop, also because a 4-bet would put me in a difficult spot..

The weak turn bet meant s0mething like a test bet of 2p/straight for the flush, so I slowplayed and just called. Stupid move with hindsight, giving a free card to 4,9 or 10 outs

River is probably standard. I assume I should fold easily against a decent reraise?

Prima Poker skin
No Limit Holdem Ring game
Blinds: $1.00/$2.00
8 players
Converter

Stack sizes:
UTG: $159.00
UTG+1: $493.48
MP1: $235.72
MP2: $86.72
Hero: $642.70
Button: $41.20
SB: $192.88
BB: $384.30

Pre-flop: (8 players) Hero is CO with 8 7
3 folds, MP2 calls $2, Hero calls $2, Button calls $2, SB folds, BB checks.

Flop: 4 6 3 ($9, 4 players)
BB checks, MP2 checks, Hero bets $7, Button folds, BB raises to $21, MP2 folds, Hero calls $21.

Turn: 2 ($51, 2 players)
BB bets $8, Hero calls $8.

River: Q ($67, 2 players)
BB bets $16, Hero raises to $50, BB calls $50.

Results:
Final pot: $167