I went through the same process on my last 4runner, actually had most of these springs on it at one point or another trying to find the right one I liked.

I used some OME chart to fill in spring rates for most of them, and confirming free heights by hand measurements. The superflex and 891 are progressive so hard to give an exact value for, but superflex definitely felt softer than the 861. IMO the 861 were too stiff.

In the end I was most happy with the superflex, and would get that again if I built another t4r.



My requirements were very similar to yours: +250ish lbs, less than 3" lift, long enough to not fall out when drooped.