If you had taken a better line this would've been an easier hand to play. Bet flop. If villain calls/raises you can narrow his hand range down. You have position so you can check behind the turn when you don't hit (after he calls or raises) if he checks it to you.

As you played the hand I would just call his river overbet. He could easily have KK, A5s, 65s, 66 here and wants value for his hand after the river scarecard hit. I think the overbet was made to represent the flush, thinking you'll call with more hands than you'd bet (AK or other big aces. Your hand is probably goood here a lot of the time, but I don't think thats the point. A push probably folds out almost all hands you beat (AK, open trips, etc.) except for a lower flush unless he thinks you're FOS. Think about it from his perspective. If he doesn't have a fullhouse or a flush here he's going to give you credit for a better hand and fold that river when you push with any other piece of the board.