When a billionaire discovers the Garden of Eden, two Biblical revisionists set out to debunk him, until they learn it might be the fountain of youth.
The concept has some interesting dramatic possibilities, but to be nick-picky, there is no mention of a fountain of youth in Genesis. There is a river that is supposed to be the source of 4 rivers including the Tigris and Euphrates (Genesis 2:10-14), so I supposed it could sub (with exposition to reconcile your story with the Biblical account).
And then there is the tree of life, the fruit of which could be appropriated in your story for the same result. And there was also a tree of the knowledge of good and evil. If you’re going exploit the Garden of Eden for dramatic purposes, have you considered using that prop as well? Pose a dramatic polarity of values and choices the protagonist will have to wrestle with. IOW: how far do you want to map the original Biblical account to yours?
Finally, if the billionaire has discovered the Garden of Eden, it seems to me that the least of his problems will be 2 Biblical scholars whose knickers get tied up in a knot as they try to debunk him. The greatest and more urgent problem will be preventing the discovery from going viral — which must be a very real threat — resulting in hordes of humanity descending upon the garden to get a bite or bath of the action.