The modern mass can be done ad orientem. The switch of orientation was only permitted, not required, in the Novus Ordo.

Most of the changes people associate with the Novus Ordo were completely optional and often not even expected to have become so common. This is why all the popes have been exasperated, to varying extents, with the Latin Mass movement. Literally nothing prevents dioceses from celebrating the Novus Ordo mass in Latin, ad orientem, chanting, etc.