Jack_Travis, the correct 6 cyl ones are KFFL-26 and the V8 ones are KFFL-52.
antigravity, part of my problem is exactly what you have - ie. with the correct "Low" rear springs the rear sits a tad lower than the front with a full tank of fuel and/or load in the rear. Also there's the "crashiness" of the front - which to be honest isn't in itself that bad as to truely concern me in and of itself, but it makes me wonder. The height I have at front is actually exactly correct XR6 spec (367mm from wheel centre to arch) - I'm buggered if I know, because I'm sure I originally measured it at about 10mm more than that (I just double checked it a few minutes ago and edited this post as a result). So yes, you'd think V8 springs would make it sit higher (?). Until recently I actually had std rear springs so this front/rear height situation has only appeared of course since the low rear springs went in.
Don't get me wrong - my handling is pretty special if I do say so myself (the wanderiness I'm hoping will be down to the Watts link bushes - which are about the only original things left in the whole suspension) - I'm really only chasing the cosmetic issue now.
I have found rear spring spacers which I've got on order (along with new Watts link bushes) - they are 10mm thick, made by SuperPro and can be bought from Whiteline. The Part Number is SPF252-10K and cost about $13 each (before GST and freight). I'll probably fit them next week, along with new spring mounts - I'll let you know how it goes.
IT'LL GO OR IT'LL BLOW!!!