Bet 80% pot on flop, check turn and make a decision on river...probably a call.

Preflop: Obviously standard

Flop: Yeah I'd size up here to about 70-80% - lots of value to be gained - even potting is an option. you are still up vs 6 cards - people still have tons of equity - and tons of continues

Turn: Easy check-back

River: As played fold - and if you would have checked back OTT and he led that river you can prob. just fold aswell.
If villain is not a decently big fish you shouldn't have any domination on his value part of range - and he obviously can have a bunch of 8X here. In general my experience and MDA tells us that people don't go overly crazy on 4 straight runouts, MDA also tells us that half pot river bets usually are just on the value side of the spectrum.