Man how are 89 gts-t's a piece of crap? hahaha, maybe you should sell the great southern right whale.
My 89 Type M gts-t has LSD, Digital climate control, Blue tacho's and excellent condition trim which is far from 'dodgy'.
The only differences to my knowledge are the type of trim, colour of dials, front indicators and the front bumper. You will come across shitty examples, but that's the case with every car. There are some very nice 89's out there.
Best of luck with the project mate.