So, as the First and the source are pretty much different versions of the same planet, with regions of one being directly related to regions in the other, I think it's very safe to assume that the unsundered world also featured more or less the same geography as the Source, perhaps with small differences.

That being said, where you believe the main things could be located? Would Amaurot be located roughly around where Eorzea and Norvrandt are? What about Elpis? And other locations?

Those are questions that have been lingering in my mind ever since 6.0... I hope we get more info about the specifics of the ancient world in future patches