When I painted mine, I used those drawings that were posted by FY1 RT SE. At the time, I did not realize where those measurements were taken from (Thanks for the clarification, Barry!)
You can figure out your dimensions from those drawings. The 'thin' stripe is 0.20" (paint). Then there is a 0.25" gap between the 'thin' stripe and the 'thick' stripe. You can use those dimensions along the car to figure out how to place the 'thick' stripe.
Painting tip: When we did mine, we masked out the area, and used 0.25" pinstripe tape to make the gap between the stripes.
The biggest difficulty was making the stripes come down the quarter panel. As you can see in the drawings (and original cars), the stripes sort of terminate in that little bumper cutout area. A lot of people incorrectly bring the stripe to the front point of that cutout. We sort of 'eyeballed' mine, using the picture you see below (the green car with the gold stripe). That is original paint. My car is the orange one below.
If I can offer any help to you on the layout, please let me know!
-Tom
