There are a lot of people who took all the components from a Mk2 setup, and simply used the 1500 block instead. Of course, no oil squitter's, etc, but it seems to hold up as long as you don't go crazy with boost (over 1bar - 16psi)
The parts offered by MWB would be a great start. Although the turbo is a older design, it is a good size/configuration for a low boost conservative build on these engines, with almost no lag. So long as the blades aren't damaged it can be rebuilt and rebalanced. Then if you utilize a aftermarket adjustable wastegate actuator with a boost control valve, along with a larger more efficient intercooler, it will be a great system. That ECU and O2 control is also a old design but a excellent brand so it will be more than sufficient for this purpose. Programming will be needed for your specific setup. You will also need a multilayer steel head gasket (apparently the reason this system is for sale), which is available from a couple of sources. I can't tell if this offering includes all of the necessary sensors and other bits, and I don't see a crankshaft position trigger wheel and sensor, nor the ignition system. But anything that's needed can be added. And the price is good for what you will get. This is very similar to the turbo build I have been assembling for a couple of years (I work at a snail's pace). There is a good thread on turbo systems for the X if you wish to get more info on the subject.