In the restoration of my 1965 Dartcharger at page 120 or so (look at April/May this year) I have mentioned this. You might use that if you'd like. I would not had my car judged at all if the tag wasn't there in the correct way.
I have put 10 year of searching info and found only what is mentioned at allpar.com.
Hope everything goes well for you. Let me know if I can be of any help.