It's already been done.
I somehow doubt that a movie about the Pax Romana under Augustus Caesar would be very interesting since nothing really happened during that time, up until Claudius was born.
Sure, the Tiberius years were very interesting. Mean, crazy women, carnage in the imperial family, wars and insurrections, basically the whole first section of Tacitus’s “Annals.” And Arminius’s massacre of Varus’s legions took place in Augustus’s reign. That would make a great film.
The whole Jewish rebellion subplot started off interesting but was abruptly truncated. Sounds like Heller had intended to do much more with it in the fifth season. Would be an interesting topic for a feature.