Did you try SMS Auto fabrics out of Oregon? If anybody has the correct material, it would be them!
Also, for your reference, the only 1967 Barracuda Formula S 383 automatic convertible made was blue on blue, with a blue convertible top! A member here had owned it and offered it to me, but it was a big project that I couldn't take on! It also had blue headrests on the bucket seats, an almost impossible to find color option. She sold it not long ago, I hope it found a good home and is being redone!