Don't confuse the GTS with the GT5. Two entirely different cars.
Regarding the sherpa question. California is the epicenter of the Pantera world in the US, if not the world. Its highly recommended you have a sit down with an owner and talk about the ins and outs of the cars. Its also recommended an experienced owner inspect any potential buys.
And, yes, an '89 model can make it through the stifling California system depending, of course, on any modifications that may have been made.
Kirk Evans, who created Amerisport, was key to the importation of cars for the US market. You can find him on this forum.
The Pantera market is a bit unique. Where Corvette, Ferrari, Shelby, etc. prices are heavily dependent on originality, the Pantera, not so much. A very original, low miles car can get just as much money as a well executed modified car.