well I've thoroughly ripped apart my cougar and am using a mix of contour and cougar wireharnesses for the cabin/dash. The crossmember may be a bit different, but thats not that difficult to swap out. The wiring should be plug and play (apart from slight differences with the later cougars)... although I haven't tried it, but I want to say even the gauge clusters are swappable. The dash itself will fit without issue. but obviously, you are going to have a bit of fiberglass work on your hands to mold up the door panels in a way that doesn't look awkward.
I have plenty of photos of every part if it interests anyone.