Any turbo 350 cable should be the proper length, but you may need to adjust it. Get one from a scraped car, or go with this one: http://www.rodworx.com/product.php?item=115
Most 200r4s were behind 6 cylinders. Unless this is a Grand National tranny, it's probably not very strong if stock. You may be able to make some money on it.
Sorry to hear Pete, and the rest of you with back problems, I couldn't imagine how much pain it must be. Please keep your spirits up, and don't let it get you down!