The landcruiser springs are too much if you just want to level it out. I have them and it raised my rear end 2.5". Plus you'll have to do some other mods if you don't want to drive around with it all offset and the brakes not working right. I had All Pro springs in the rear when I got my truck and that was level. So you might look into something like that if you don't want added height. If you do end up going with the landcruiser springs, you will need a bigger tire than 31's. They'll look really small in my opinion.
This is mine level in the rear with all pro springs and no jacking of the torsion bars, with 32's.
And This is mine 2.5" taller with land cruiser springs in rear and ball joint spacers in the front, plus the torsion bars jacked, with 32's still.
The other thing is that your ride is going to be a lot more stiff if you jack the torsion bars.
The springs should come from the rear of the landcruiser though.
If I had to do it over, I might have gone with leaf springs in the rear and ball joint spacers in the front.
But it's really up to your taste, so you just have to figure out what you want.