For your information, I am attaching copies from two pages of my 1967 Color and Upholstery Book. When I purchased my book some 30 plus years ago, there was a separate brchure included in it on the Comfort Weave. In addition, there was a sample, approximately 3" x 7" of the Parchment Comfort Weave. I have attached pictures of the brochure and the front and back of the sample (which if held up to the light, one can see that light passes through it.
As for availability, it appears that it was available throughout the Model Year, as it is shown as an Option in the 8/66 Sales Brochure, the 1/67 Sales Brochure, and in the Soft Trim Section of the 1960-68 MPC, on a page dated October 1967, with no caveat of "not available after a certain date.
Hope this helps.
Bob