Here are some pictures for reference. These were taken from a survivor 69 Pace Car, with its original paint and no door decals. This Pace Car has been in the same family since new.
As JohnZ can confirm - there were guides uses at the assembly plant to help locate stripes, but they were applied by hand. So variation from car to car is to be expected.
The D96 pin stripe, as defined in the 69 Asm. Manual shows the front fender stripe starting 0.08" above the fender extension seam line but notice where the one on this car starts. Perfection was not the rule when our 1st Gen cars were built. The stripe was to run 0.25" above the fender-door peak line and end 27.5" in front of the rear edge of the door. The manual shows the wider bottom stripe to be 0.12" wide, a 0.12" space then a 0.06" narrow top stripe.
The rear pin stripe follows a similar pattern, starting flush with the bottom of the rear louvers (see pic) and ending 1.35" from the rear quarter peak line. However, the Assembly Worker who did this Pace Car stopped about 3/4" short of the back edge.
Good luck with your project!