Have you looked at Kennedy Engineering? They may have an adapter, the rest you'd have to fabricate. I do have to ask why you'd want to? With all the other options that are readily available poking that very old design into the back seems a little unusual.
Personally, I went with a subaru EJ25 (2.5L NA drive by wire) and that gets me down the road with equal to or almost (depending on the 944 motor) horsepower and none of the Porsche headaches or dollar signs.