Rich, Since you still have the original cover, I'm sure a local shop could stitch up a replacement for you to install. As you know, there's only one line of stitching on the entire seat cover - at the front.
Ask them to leave some extra material around the perimeter. Helps to have enough material to tug on as you
heat n' stretch for a good fit. You'll trim off that extra
after the install is completed.
And, Thomas Fishypaws... that is a non-stock R65 seat ya got there. Could be the original pan, but... the N'west or Motobins covers would not fit the presently installed foam.
Monte