Hi.
Mixing any kinds of different cabs is always a hit and miss usually for reasons other than the porting (or the lack of it

).
Trying to match a combo speaker/enclosure with something else is even harder s there's no way of telling the sensitivity or any other important figure of a combo.
IME any cab will vastly improve the sound of a combo rig (as long as all the speakers are in phase), so the Ampeg will probably be as good as any other cab in the same price range.
Regards
Sam