This heavily depends.
Take a look at the Movie Alexander the Great. While the movie is decent and quality, it just kills the idea, because everything is "cut away" - its more like "highlights" of his life. It definitely would need 3 movies here, instead of one, where everithing is cur away.
But sometimes they expand too much like the Hobbit - forcely expanded to 3 movies, where there could be 2 and it would be much better.
Maybe putting it into 2 roms would be the best idea, it depends how much content you have.