[surfbeast]

You can pretty much mix and match all the parts from 96 - 98, body/interior wise. You will have to do MAJOR mods to use the cobra motor though. Unless you have a big budget, a big shop and major mechanical knowhow you would be better off just buying a 96-98 Cobra. You would be happier in the long run.
The cobra engine requires the cobra computer ,harness , transmission etc.. The bodies will except the motor and bigger wheels you mentioned but the engine change is costly $$$$$$