I bought a NOS high pressure hose on eBay. Fortunately when the new fabric covered hose didn't fit, the factory hose and restrictor device/union were reused. It sure would be a pain to try and install a restrictor and sleeve now. I could not imagine trying to pull and replace the steering rack with the engine in the car. It almost seemed to be an impossible job.The sleeve came from McMaster Carr.
The big low pressure supply line came with the restrictor from the factory. I don't know the science behind it, but I'm sure its there for a reason.