You have a mess on your hands is what I think. I hope you didn't pay GTS prices for it.
Something is not as it should be. It's not an odd ball factory build. You need to think about what you want to do here. If you dig to deep you may find something you don't want to find.
If the car was stolen with a vin swap, what will you do. You could keep your mouth shut and enjoy the car, but any money you put into it could be at risk.
As it is now... It's titled as a 68, but it's clearly a 69. It's not a 68 GTS. It's hard to say what it is.
This is one of those really bad situations.
You have several options....
Some legal and some probably not.