The chrome side script really isnn't a "font" as such, but was hand lettered by the company that made the emblems: ACSCO Products of Burbank, CA. ACSCO made the Cobra roadster emblems, Shelby emblems, and even the '67 hood cables, '68 Shelby and GT/CS hood pins, and '69-'70 Shelby Hood pins (also used on the '70 Hurst Olds). I have a blueprint of the CS side script, and a copy of it appeared in my first (1988) book.
Ford didn't like the idea of script, but they relented, and in doing so only gave ACSCO 2 weeks to hand make sets for the prototype cars for the Feb 15th unveiling. You see....Ford wanted a stripe around the tail of the GT/CS like the "Super Bee"( that also came out in the spring of '68). The Calif . Ford dealers didn't like that, and said no script--no car. So, Ford let then have the script.
The stripe "cutout" GT/CS lettering isn't a font either--as that was hand lettered by Shelby Automotive in Michigan. The closest font used could be one called "Claredon".
Since I'm also a graphic artist, I've had a side interest in what they used.
Just some FYI for ya.
Paul.