I had a friend at the Portland Swap meet that owns an S code 4 speed GT/CS. He is a local restorer, and seller every year at this event. I had him and his son scour this 4 day swap met that is one of the largest on the west coast every year.
No big block parts or GT/CS specific parts were seen that would lead to the stripping of your car. A few trinkets here and there. This is a good thing in my mind.
I don't know why, but I feel your car is still close to your home. Hidden and waiting for the heat to go away. Dang it.
Have you though about a large page ad in your local paper? Not sure what social media you have, but have you tried that? Someone saw something that night or day when it left. I hate to ask, but how reputable is the storage business it was at? Are there other high end cars there and have they lost any before?
Somehow, I bet you have tried all this, but I had to ask.
Rob