Hi Leo,
What condition is just the waffle section of the panel? From the image provided, you may be able to clean up the waffle section and use it as the seat belt attachment and shelf slide receiver are surrounded with chrome and the bolt through the wheel well is covered by the back frame.
A while back, my original quarter panel plywood was coming apart and the front section near the floor was really tattered and brittle. I recreated the wood and metal panels (as I think you did) and reupholstered by cutting the waffled vinyl and sowing it to new black vinyl I found that exactly matched the grain of the original.
One caution, however, when installed, the rich black of the new vinyl made the original door panels black look shallow as a result of its exposure to light and age. As a result, I was forced tocontinue and created new a new interior. The only parts that stayed original are the seats (front and back), cubby cover, and waffle section of the fold down shelf (along with the waffle of the quarters).
Since you have already recreated the supporting panels, I would take the chance of doing as I had. You can always buy new if it turns out to be less then satisfactory. If it looks good, you will have saved quite a bit.
Good luck,
Ray (64BJ8P1)