What parts are interchangeable between 95 stangs and foxbodys?

Depends a bit on how you want to go. The 5.0 block and heads would work easy. The water pump is different and I believe the timing cover is as well. You can keep the Fox TB style intake as many on this side of the forums have swapped in favor of that setup (myself included). If you run the internal EGR of the Fox then Fox headers will do you fine ('94-'95's stock have an external EGR with a pipe that attached to a bung on the passenger side header).

Feel free to put your Fox upper and lower control arms on a '94-'95, but our brakes and axle lengths are different. The '94-'95 brakes are better than a stock Fox, but if you've done a 5-lug Cobra upgrade, you may want to take the rotors and calipers with you.

Umm. . . I think that's it.