Here's the non-PS's subframe (sorry for the bad pic, but if you look close, you can tell that it's flat, and not concave like the other one).

By the way, you'll also need the little universal joint that connects the steering shaft to the rack. The PS racks have a larger geared end than the non-PS so one side of that joint is larger for the PS rack. Probably be easiest to find a car in a junkard and pull everything, the subframe, the rack itself, all the soft and hardlines and the pump and tank too. Hopefully everything comes out okay and works but honestly, it's not that much work turning the wheel over.