I had a 70 Grabber Sportsroof that had reverse C stripes just like a 69 Boss 302 (without the words) and look similar to what you have painted, so there was a 70 Mustang with similar striping available from the factory. FWIW
Here is one - mine didn't have a vinyl roof, have to say I am glad it didn't

Mine had a blacked out rear tail panel just like the Bosses but had standard chrome taillight bezels, not blacked out like a Boss.
http://www.mustangmonthly.com/featur...ang/index.html
actually, just saw this, the first image is exactly what mine looked like when I bought it right down to the hubcaps and is directly out of the Mustang Recognition guide IIRC
http://forums.vintage-mustang.com/vi...-c-stripe.html