The Marti report for a 67 would give it away, though.
I'm assuming you just want info for where the stripes are, the pins are and such. There was a good article in
Mustang Monthly that gives some good info on where the side letters/emblems. As far as the stripes, you can buy them as decals from most Mustang suppliers and fit them before permanently adhering them. The stripes could come with the rocker mouldings unlike the previous years. You will need a different rear valence with dual exhaust cutouts at the base and quad tips if you are trying to replicate an S-code, A or K GTA (I think you could get an auto with the K that year, but few K codes were sold and most were fastbacks and 4 speeds). The foglights and corral are also unique to that year. As far as a book, the one by Tom Corcoran
on Amazon or your local book shop (?) is a great one for giving illustrations and other things on the GT and GTA.
Summary: the GT equipment group (fog lamps. power front disc brakes, dual exhausts with chrome quad tips (excluded on the 200 hp 289), GT gas cap, the handling package with the stiffer springs and larger swaybar, rocker panel stripes and GTA emblems are all available from NPD and other vendors.

The power steering is the same for the "plain" cars and the GTAs, but if you have manual steering, you will need the 16:1 box to be "correct". You can also add other exterior items like the turn signal hood and styled steel wheels to give it a bit more sporty flair.

It really depends how close of a clone you want to make to what items you add.

Daniel