Ford used a "power assist" style power steering back then. It used a hydraulic ram mounted to the tie rod, with a control valve on the end of it. It worked good when new, but as it aged, it was more known for leaking fluid. You can get most of the parts from a Mustang supply and adapt them. Borgenson makes a replacement power steering box for early Mustangs that you might swap in, but they are pretty expensive. I don't know if you have room for a GM Saginaw style box, they are a popular choice on older vehicles.
You could just run the pump, connecting both lines together I think. It will burn the pump up if you run it dry, so the lines would have to be connected, and you might even need a reducer to slow the flow.
Only other thing I can tell you is to find a set of single groove V belt pulleys and let the alternator be the adjustment point. You would need the get the set off of the same engine, Ford used dozens of different pulleys with different offsets, as well as the pre 1985 crank pulleys being 3 bolt, and the post 1985 being 4 bolts.
