how can you put him on a proper range when he was in the BB to find out if its +ev he likes his hand now thats all you know. 2 pair, sets, and 35 for a shit straight could easily be in his hand. when he leads out on the turn are you hoping he checks the river. I think its a fold. if he overplays top pair like this it won't be hard for you to take his money in a better spot.