Ranger, BII, and Explorer.
If you are looking to get everything in one go, a Ranger or BII with the same engine and power steering.
From anything else you'll have to piece it together. Power steering gear box should be the same 1983-1997 on the Rangers, not quite as long on the Explorers, and was used on a lot of other models. You'll have to figure out the bracketry for the power steering pump, easiest would be to find a donor with same engine at salvage yard. Being an 84 you've got a 2.0/2.3L gas, 2.3 diesel, or a 2.8L V6. Hopefully you've got the 2.0/2.3L gas because it's going to be the easiest to get power steering brackets for.