I`m probably going for a S13 rack, and just cut it a little. My box orginal box is shot.
I belive 2" to be the most you can posibly move it. Probably a little bit less if you dont want to use a hammer.
It worth noting that the subframe sits realllllly low under the car. about 1,5 - 2" lower than the standard x-member. I realy did not care, since I get the motor as low as possible in relation to the body. But it is realy the lowest part of the car by far. Also the 120y mountingpoints for the caster-rods gets way to high, so s13 ones will have to be used, or custom fabricated.
I`m also planing the s13 irs, but dont have a welder in my little garage, so will have to wait... :)