That is so wrong on so many levels. All that power with those skinny tires, and all that weight up front. Handling had to be just terrifying. I am assuming that there had to be some major surgery to the chassis to squeeze that engine in, and in locating the Jaguar diff. all of which would compromise the structural integrity of the monocoque. Mike will certainly be able to advise how to put that back right.
I have a S1 Elite, that I restored a couple years ago. When they are set up properly, they are just fantastic cars to drive and are just beautiful cars. You do have a lot of work ahead, and lots of driveline parts to find. It will be worth the effort. Good luck, and if you need any advice ( for what it is worth) you may contact me.