There were hoses that I just could not find to buy when I put my 81's system back together, specifically the 2 that connect to the compressor. I had them made up at a hydraulic hose shop for not too much money, around $140 if I recall correctly.
What style compressor are you using? I have been through 2 York upright compressors and will not have another one. I don't know if it's the fact they have only 2 cylinders, or what. But they both produced a weird harmonic in the belt that stretched it within an few minutes of running it. Then of course it would throw the belt. The oscillations were scary to watch. I don't know how these systems ever worked in the 80's for any amount of time. I guess they did though, and I have 2 duds in a row, or else there is something else fundamentally wrong. If there is, I can't find it. All the pulleys are in alignment, tightened properly, etc.
I have given up on that system, but I'm building a new motor for the truck and it will have the '95 serpentine belt accessories, one of which is a modern multi-cylinder radial type compressor.
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
92 F150 RCLB 351W E40D BW1356 mostly stock