If you were calling for set value only (being out of position, and as it appears) - then I'd just lay it down. Especially since you have no read on the guy. He could be playing 78 this way, or a pair of 9s, AT, who knows.
If you were playing as an overpair, then why not bet the flop 2/3 or pot? Unless you wanted to check-raise in which case go for it and see if he's smart enough to fold or reraise. Though with the lack of information he has from you there's little chance he would put YOU on an overpair.