Wouldn't the reconstructed version of the person be but a shell? With no soul? A facsimile with no one home?
I love the thought of a portrait being a portal. It sounds like a magnificent idea for a poem, a book, an opera, or some other work of art.
A good portrait, in my opinion, reveals the sitter's personality, and tells us a lot about the person. Unfortunately the communication is a little one-sided.
"The philosopher proves that the philosopher exists. The poet merely enjoys existence."