[BluffTHIS!]

Since the game is shorthanded, as most of them are at the bigger plo tables on UB, and since the opponent never on the flop or turn acted like he had a hand other than a draw or an overpair, then yes I would call but I wouldn't like it. His river bet did have the smell of a busted draw, but some players here even headsup would also slowplay the 98 straight and see if the flush came or the board paired.

However this situation on the river would have been much easier if you had correctly checked behind on the turn, taking a free card, because of the possibility of draw vs. draw or that he had a set and feared an 98 straight, and because of the flush draw present. Had he had a flush draw as well, then his hand probably would have been a slight favorite on the flop. Plus you also avoid being checkraised off your hand. Checking behind was also the play that best preserved your power of position since he then wouldn't have been able to set himself in on the river without fear of being raised and put the decision on you.