Wow, I looked at quite a few sites. Nada. Guess not much call for aqua dash pads.I got one of the last factory-dyed Turquoise dash pads that I know of from a Mustang parts vendor about 17 years ago. Dashes Direct makes about the best you can get, available from NPD (and others) and I believe I would choose a light blue one, prep and dye it to Turquoise to match your door panel color.
I'm unsure how the exterior color code relates to the interior dash pad color.. But bottom-line, dash pads are available in black, dark red, and blue for 1966 (and also they make them in the 1965 bright red, as I guess there's demand for that).