I don't think the conversation is there just yet - before someone can give you any kind of good advice they have to know your intentions and understand why the coils aren't working for you.
So turn that around a bit - what problem are you trying to solve?
I bought a 92 FJ80, engine runs, truck drives, but pisses oil all over. (Which isn't really the reason for the Cummins it's just kind of ancillary) Only paid 1k for it though.
Plans are to pull the engine/trans/t-case and fit a 5.9 12valve ve pump cummins with an NV4500 and NP205. Will remove stock fuel tank and fit in either a custom fuel cell or a tank from another vehicle. Will then be running 60 up front and 14 bolt in the rear, both with ARBs.
Intentions are to make it a mild crawler, lots of desert exploration - solo, all purpose rig with good road manners and the ability to drive rural Nevada highways at 65-80 mph for hours on end.
Front suspension:
Radius arms would seem a decent choice, as would a properly set up 3 link, however leaves also seem like a viable option.
The rear I'm pretty set on running leaves.
I know I'm re-engineering the wheel here but hey!
I guess I ought to add, I'd probably be happy with some simple bolt on lifts for the stock axles/links but because of the torque and weight of the cummins I'm not going to waste time messing with axles that will likely break and break when I'm in BFNV.
Also.. I'm not trying to knock cruisers or their axles. I bought the FJ because I love Toyotas and I've always like the 80 series, I however want a powerful diesel engine. I do know the stock axles hold up quite well to abuse but I know they won't hold up to what I'm after. So here we are.