Mate, you really need to talk to an engineer. Seeing as you're from Qld, you're going to have a hell of a time getting it legal. Nothing's impossible though.
Before a proper answer can be given, we need a bit more info. How good are you at fabbing/welding/hitting things with a hammer? What you are proposing is a fair bit of work and should not be undertaken lightly or have corners cut.
What power steer options do i have available to me? I see the americans use the toyota IFS boxes but what cars do these come on?
You can use pretty much any power steering set up. Depending on what tyres you want to run. Vit/Jimny are both good options.
Landcruiser boxes are another option as the 60s and 80s have forward facing pitman arms so you can mount them further back on the chassis which is handy if you are moving your diff forward. FWIW I have a ford falcon 'teardrop" pump and a 75s box sitting on the shelf.
IFS boxes come from toyota hilux and 4runners that have (gasp) IFS. They are readily available and complaritively cheap, hence their popularity in the states.
Is it worth buying a kit to do this or would it be better to fab up the mounts and everything?
Cheap or convenient. What's more important to you?
Do the hilux diffs knock on anything at full flex that the standard diffs dont?
Not if it's built right. Although I'm not sure what they could possibly knock on anyway.
Is the process between converting these diffs on NT the same as WT?
Pretty much although every job has it's individual quirks. I'm definitely no expert though. The NT and WT chassis are the same, the WT just has the spring mounts outboarded.
It sounds like a pain in the Twisted Evil to cut all the mounts off these diffs
What tools you got? Plasma and a grinder = not such a pain.
Pretty much every other method (I used a grinder only) = very painful and time consuming.
Well, in my case anyway.
