Not sure what your using as a reference (hopefully not that Mustang Details paperback
The service replacements for a 390 fastback 4 speed with only PS was Orange and Violet
In addition the Add/Delete sheets from Shelby build groups early in the year (Jan period) indicate that the regular Mustang front springs for the application were replaced with others - specifically C7ZA-5310-N. This changed later in the year
Seeing you have a pretty early built car and it appears (from original cars) that the springs changed (or at least their markings did
a minimum of three times during the production year the closest car I have to yours, equipped with the same options had a single Orange stripe. As always yours could have also included the over or under rating stripes but the majority of springs (IMHO) did not include these other marks
Hope this helps