the GT is the same as the LX. about the only thing different i can think of is the seats (depending on what year, material and what your car came with). the 4 cyl LX cars have totally different seats than the LX 5.0 however the GT and LX 5.0 are quite similar. oh and the GT will have a different headlight switch because of the fog lights.
If you want to make a GT, i have a great full GT body kid and tail lights that I am trying to get rid of.