Not particularly hard to refurb to be honest, as long as it's not completely knackered e.g. damaged compressor blades from touching the housing.
You have to be very careful to mark everything e.g. positions of compressor and exhaust housings w.r.t the the core, and the position of the compressor wheel w.r.t to the turbine wheel, and the position of the nut w.r.t the compressor wheel (since the nut is ground down to balance the compressor side).
The most difficult part is getting the compressor wheel back into the same position on the turbine shaft, marking the shaft and wheel with e.g. a marker pen is simply not accurate enough, and you must never scratch marks into the shaft or wheels. I built a simple U shaped wooden jig that could support the shaft from the centers machined in the end using woodscrews, and with a fixed and moveable pointer. That way I could line the pointers up at the edge of one blade on the compressor and one blade on the turbine wheels, which were then marked with a marker pen.
Changing the bearings and converting to a 360 degree thrust is easy once it's disassembled, but obviously you have to make sure everything is very clean when reassembling.
Mines just coming up to 24k miles since I rebuilt it, and still going strong with no sign of smoking or nasty noises etc.
I would consider an upgrade to a T28 sized turbo though, preferably one of the more modern variants.
