Well, it really looks he has that flush too, especially with the check on turn. A full house would be surprising, unless he wanted you to complete your draw but based on your read, he's not that much of a thinking player.

Now, if you know he can push the river with only an 8 or some weak flush, you have to call. But what was he raising on flop, a pair of 8s?? A set? (then checking turn?) He's mostly on that flush draw himself i think..

I think you can win river no more than 50% of the time.