Unfortunately, there are multiple errors in the work you cited. The correct color is listed as simply "Black" with the PPG number that I gave earlier.
Given the many mistakes in the book, I would also guard against using it to determine which parts were painted a particular color. As you note, the chart lists only 65/66. And while 64-1/2 Mustangs might be considered 65's by virtue of their VIN, the fact remains that there was a definite transition in interior trim at the beginning of the 1965 model year in August. As much as possible, I would use original vehicles with this color as reference material, until a correct accounting can be made.