Amazing work. I'm impressed! You've given me some more ideas for my ongoing project
AriuSen: Regarding spring rates, although I'm not at your level with grip, my power level on corner exit and 'street' tires never kicks out like yours does on the track (or did). I have stock rear 3.0si bar, standard coilovers, but with 504Fr/672Rr springs and no LSD, car was sticking like a mad man on corner-exit full throttle (and 500wtorque from the 2J).
OP: But, at " 700 lb front, 850 lb rear.", I too agree this may be too stiff for the chassis especially if it is now 2800 w/driver. Nothing wrong with trying it, but you'll have some options and experience from a few of us if you run into issues. Just another datapoint...