When I did mine, I got my adapter fitting from Heits. You will also need too bypass some pump pressure, do to the high pump pressure produced by the GM pump. Some ford power racks will blow out seals due this excess pressure. They sell an adjustable bypass block, which bleeds off pressure, and in turn it will allow you to adjust the steering effort at the steering wheel. I have done this to three cars so far, and they still work fine after several years. (no leaks)

http://www.heidts.com/
hope this helps
Bob