I'm glad you lads understand the circumstances.
Looking at $7k mark.
Good buying on an appreciating asset, with some good JDM mechanicals.
Sad, but understandable.
Okay, so I'm sorting out my diff.
Going to use a R31 auto diff (28 spline, 3.9:1) with the KE70 mounts relocated onto the diff. The diff itself is 60mm wider, so I'm going to find some +30 offset rear wheels to combat the extra length (or run bolt on guards) Then i'm going to buy a MiniSpool for $99, and bung that in, followed by mounting 2 sets of VS Commodore calipers on the rear (One set dedicated for Hydro handbrake, and the other for normal handbrake) Adjustable panhard rod, with KE70 mount switched across.
Jase / Josh / Techheads? That wont break behind a CA18 will it? Lol.
Maybe not in a S13, but in a KE70 that weighs 800kgs, with a bit of encouragement (re: boost) I don't think im going to have a choice in the traction debate. Might even go for 9" rear wheels with some CHUNKY rubber on it.
Two calipers? WTF.
Are you sure the Commo rears wont give it too much bias? You might need to investigate front calipers piston size and master bore size to make it all work (Pascals law if you are into physics)
You have 800kg car so the R31 is enough. Even with eleventy billion fasts it will just break traction. You could put a Morris 1000 diff in it and I doubt it will bust it.
9''? Doubt you will have enough torque to turn it. Leave it for the real cars like the V8s.

Turbocharged or supercharged?
Why don't we have both?
dumb arse train driver thought it was s good idea to mash the go pedal (lever thing) like he was racing the train beside us, we get to our platform still smashing along when he realises, smashes the breaks and we just skid through it and had to go to the next station in a train that smelled of burnt brake pads :S grrrrrr. another train back the other way now.
*brakes