Maybe you can take the guts out of it and put it back on...
Had a similar issue with a '92 F-700. The beast had a 7.0L gasser with two air pumps. Driver's side pump locked up and put the truck in unusable for because the hydraulic pump for the brakes piggybacked off of that pulley. I took it apart, and got it freed up, and it seemed like it would work, but was then sent to the dealership for a new one. Dealership charged $700+ for the thing, and they ordered the one for the passenger side of the engine ,so it took another 3 days to get the truck back on the road...
If you can disassemble it, remove the vanes and such, and essentially make it an idler, that would be the cheapest functional option.