The model year there was 87-93, same motor (mostly) throughout and the gts and lxs then were exactly alike, cept for aesthetics.
http://www.mustangregistry.org/lx_87_89.htm
The 87 runs on speed density, 89 was the first year for mass air. The computer should work fine, its the same for those engines and the same for all trannys. I don't know about the pilot bearing though.