[jjbish]

Best case scenerio is he has Acxc maybe Kcxc and will bet. If he doesn't. Does he call any bet.

Has he kept firing at a similar pot? Your check/calling is pretty indicative of a draw, but he doesn't know what one. Could be str8, clubs,or spades.

If you lead out he most likey folds or C/r's you(good thing here, if he reads missed spades). If you check, he may check behind and you'll have no chance to extract more.

I say bet ~1/2 pot and see reaction. Probably most +ev money wise.