I did LOTS of research on 861s before I installed mine. Check out the last few pages of my build for a "review" comparing my ride height before with new OEM LC 7.5 wraps vs OME 861s. They are a "stock replacement" coil for land cruisers. The caveat is that they are designed to support an additional load upfront like a bull bar and winch. Something like 200lbs over stock and provide .25" (minimal) lift on a LC.
All of the LC springs people use on 4Runners come from the front suspension of an 80 series land cruiser, they have the same seats as our rear suspension.
Installing 861s should get your rear end up higher, giving you more down travel with the shocks too.
I've got 4xInnovations rear bumper with swing out, full skids (radiator to gas tank), sliders, roof rack, hi lift, and the same box of goodies. I've got a little more weight than you do in the rear so I would expect your truck to sit a little higher than mine with the 861s in the rear.
Lots of members here run them, Big Fish All Day, 4-Ripcord, Flemster, Gerdo, and many others.
in one of your pics, its looks like you HAVE A LOT OF RAKE? was it because you didnt adjust the front? how is your truck standing now looking at it from side?
one advantage for me is i can adjust my dampening so maybe the 861 can ride little smoother