The casting I most dislike would be Montgomery as Quark. I don't think he could pull it off, too young really. I'd shift Billingsley to Quark, Keating to Odo and Mont to Bashir. Mont as Bashir is a much better fit, a young officer full of life and youthful exuberance. Billingsley has a better force for Quark and seems more likely to handle the role. Keating has that grumpy manner and voice that would match Quark.
Additionally I find the Quantum Leap
stuff to be pointless. Early on the series I wouldn't care about a little wink to the show but the constant references to a show that has nothing to do with Trek just make me want to rolleyes.