You may be correct, but the reason i wrote "IMHO early 67" is because I have in my possesion two original export braces, both with evenly spaced holes. Both where removed from rusty cars (Mustangs, not Shelbys) on a wrecking yard in Sweden around 20 years ago... one was removed from a 67 and we marked it with tape and "67" because it was somewhat different from the 65/66 one. The outer edges were just a little bit lower. It could of course have been put there sometime by a PO but as I have never heard of any differences on the braces from the early (65/66) cars.
Just my observations - hopefully there is also other info in the posting that maybe interesting for someone?