Hurtle's (who is a VMFer, BTW) is really the only first-generation registry, unless you have something really special like a Shelby. There was one used to create "In Search of Mustangs..." book, but it wasn't on-line and you gotta buy the book to see the results (~$20).
I didn't mean to say that yours isn't comprehensive , I was just trying to find a reference. Actually, your's seems quite comprehensive. Also, I was just wondering if there were others out there or if there was an official Ford registry. I look forward to having the first NM car in your's.