EDIT: I have now had the full conversion and have edited the list below
And Yes I've searched and googled.
I have a 1990 brumby and two EA81 P/S equipped donors parts cars.
You need AT LEAST
1) the PS steering rack, boots and ends etc
2) the larger support bracket ( see below) or here http://www.ausubaru.com.au/showthread.php?t=25836
3) the 4 bolt plate attached under the engine crossmember that enclosed the rack On the non-ps car this plate will have 2 bolts and two spot welds. It will need to have its two spot welds drilled out so it can be removed to fit the thicker PS rack. On the donor car this plate will have 4 bolts, and it can be reused on the receiving car.
4) the PS pump, with front and rear brackets and lines
5) the P/S pulley
6) The longer belt
7) the different thermostat housing that's longer to clear the P/S pump.
8 ) longer radiator/thermostat hose for new PS thermostat housing.
9) the smaller universal joint that connects the rack to the steering column
OPTIONAL dependent upon the receiving car.
A) the whole engine cross member (including removable skid plate) - as some cross members would not take the rack's "U" bracket due to the width of the bolt holes being different.
B) A triple engine crankshaft pulley - if your engine only has a single or a double.
C) If you have a crankshaft fan, this is a good time to replace it with one or two thermo fans. If you have A/C you already have one fan. If you don't have A/C you can install both the A/C fan and another elec fan. Some MYs had electric fans without A/C being installed. see here Alloy radiator install
D) check the drivers side head for the threaded holes the pump bracket needs to locate into. These can be drilled and tapped if necessary.
E) If your car is lifted you will need to extend the steering shaft Uni joint to an appropriate length. There are several ways of doing this, depending upon the height of the lift.
PS bracket on left - standard on right
They are essentially the same but the hard lines on the P/S rack are different obviously.