I have been searching very hard for brake rotors for my 73, but apparantly, no one has these anymore.
Unfortunately, you probably won't find any "new" brake rotors for the '70-73 design.
However, you will likely find good used rotors that are still within spec. Have you tried any of the vendors at http://www.imperialclub.com/Part/Yards/index.htm ? I would think that Bob Hoffmeister and Murray Park would have these rotors available, and perhaps other vendors on the list as well.
Good luck!
Elijah
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