Dudley: The imprint of the stamp is fairly faint and locating telltale scratches is very difficult, even with the USB scope. I added a shot taken of the location you suggested and have to be somewhat generous to call these 'scratches' but this along with a faint scratch in the upper left of the stamp Doporto points out make me 95% sure it is a 99R7. Thanks for the help. It was a fun find and what makes this hobby a bit of a treasure hunt too!
