Jeff -
Personally I think it's an intriguing car because of the stamped SPD. I would think that a pre-production car would have been built closer to corporate HQ, and an SPD is not necessarily the date the car was actually built, so it could be a mis-stamp. Date codes on any surviving OEM parts would be good info. But you could possibly have something special there if a really early production date could be confirmed.
I doubt anyone could pry off the dash tag without damaging it, but if you can look underneath, check the backside of the rivets. Light scratches on top of dash could be from someone just sliding junk across it; gouges might be a theft or swap attempt or God knows what. Dash tag was likely removed to repaint dash.
Same SO# on radiator support?