I know what you mean about not being able to find info on these engines, they are rare in this part of the world.

You might want to get new timing belts while your at it (timing and silent shafts), and inspect your water pump. RockAuto has just about everything you would need for this engine, I got a reman water pump from them.

I think there are some differences in bracketry between all variants (ranger, R50, and mighty max) but the ram 50 is technically a mighty max, so those may be similar. But the turbo setup should be the same among all three, for something that expensive, its likely ford would have preferred to mod the truck instead.

The turbo is an internal wastegated type, and they have been known to rust, but usually its in the closed position, potentially causing overboost problems, hence the blow off valve on the intake. If you look down past the climate control airbox, you should be able to see the actuator for the wastegate. and if you're really lucky, you might be able to squeeze your hand in there to see if the linkage will move, its normally quite stiff (if the truck is non AC it will be easier).

I would take the intake line off the turbo inlet to see if the turbo is stiff, or if it even moves from idling the engine.

There is something else to check.

If you look in the intake manifold, there should be two small hoses plumbed into it. One goes back to the wastegate actuator, the other goes to the injector pump. The injector pump then has a line connection it to a vacuum source through a "gismo" on the driver's side fender. This "gismo" has has rubber connections that are prone to rotting. If there is a vacuum leak here, than the injector pump gets a false boost pressure reading, and will not give as much fuel as it should. To test this possibility, you can simply bypass the "gismo" (I have no idea what it's purpose is), and see if there is a difference. We ran our ranger with, and without that thing connected, the only difference was slightly more low end torque with it bypassed.