It's a scarce and desirable postcard. I've seen one or two. There was one in a MastroNet auction a good number of years ago, and I don't remember what it sold for. I don't know that its officially cataloged, but it is a hobby known issue.
I've had an example on my site picture for several years.
I would guess you could get PSA or SGC to grade/entomb it, as they grade uncatalogued and catalogued postcards. They would just have to be confident it's a legitimate/vintage issue. If you included a copy of the relevant MastroNet auction page with your submission, that would be proof of legitimacy enough. I know it's pictured/described in an old catalog, I'm just not sure which one.