I have never noticed that Plato was "dualistic" in his thinking. He seems to have been entranced by visions of Oneness, of Wholeness, with the divine ruler at the top of the hierarchy of Being. He got to the insight without the (direct) aid of Christ -- who was some four centuries in the future. I figure he did pretty well, all things considered. Certainly, he understood the idea of the Logos.... Or so it seems to me.
This site goes down soon for maintenance. Expanding these remarks will have to wait.
Meanwhile, thank you truly for sharing your thoughts.