Not sure exactly what your asking so going to do a shotgun response in hopes that I hit the target somewhere
It could be any color (regular production option that year) the buyer wanted. That was the great thing (and somewhat negative) of buying a car in those days. Most were custom (to the owners desires) crafted by the buyer then the buyer waited for the car to be built and delivered. There were suggested charts that sometimes salesmen used but you could get anything (green car with red or blue interior) you wanted. They didn't care they just wanted to sell cars.
Now if your wondering what the original color was and its an early 65-66 car check the door tag if its original, check the buck tag if it was built at a plant that used them, find the buildsheet, pull up the carpet and look for the original color or for some plants it was written on the radiator support
If your asking because your interior color is similar to your exterior color and you need to know what the factory code is and you don't have a door tag or other ways of finding it.
#27 is the interior code for a standard aqua interior in 65