call www.phoenixgraphix.com . They make stencils and stripe kits for just about anything. They are also licensed to sell so that you will get correct fitting ones.
"Spacing and width are the same from front to back. Total width is 20". Center stripe is 10", outside stripes are 3" with 2" between stripes. I hope I explained it clear enough."
William. Thanks, though those specs surprise me. On the 2 stripe Shelbys, they start narrow at the front of the hood and go wider. I have attached a link to show what I mean. http://www.treasurecoastmustangs.com/shelby_stripe.htm