Lifts, why are they so confusing?
Because you are screwing with the ENTIRE suspension & steering geometry.
You are messing with the drive shaft & 'U' Joint angles in two planes.
You are messing with the pinion angle.
You are messing with steering link angles in 3 planes.
'Spring Lifts' mean deeper 'U' or bend in the springs,
Since your connection points didn't change that means longer springs to have the ends come out at the same points for connection as stock.
That means the spring gets LONGER that stock as you compress it...
It also means the axle MOVES forward and backward as you compress, decompress the spring...
Then there are the considerations for what you intend to do with the vehicle...
If you street drive very much, you will want a stiffer spring rate, less soggy bushings so the vehicle doesn't heel over and sway around at highway speeds...
If you are doing mostly low speed off roading,
Then you want SOGGIER springs, soggy bushings so the suspension/axle can move around where it gets the best traction...
If you are going to do both, then you want something that works reasonably for BOTH applications, which by common sense are mutually exclusive... Everything becomes a trade off from that perspective.
If you intend to street drive, keep the firmer HARD RUBBER inserts at the frame/spring 'Eye' connections.
If you want 'Soggy' to absorb odd angle and jolts on the trail, then use the most soggy bushings you can find.
If you want good street handling then use a STIFF spring that doesn't let the frame/body sway around over the axles.
If you want the axles to get a good bite off road, then use a SOGGY spring that will allow for better weight distribution over the axle ends/tires.
If you want good road handling, then use a 50/50 or 60/40 shock rate so when you hit small bumps on the pavement the shock can compress and rebound quickly...
If you want good off road shocks, then you want a shock that is quick to Droop and get weight/traction in a hole, and give you reasonable compression when you hit a rock or off center bump...
Shock bushings are even a consideration...
Again, with highway driving, you want a reasonably hard bushing so the shock gets into the game faster,
While off road you want a reasonably soggy bushing to take up the 'Small' bumps you might encounter without getting the shock fully involved...
With a lift, you have COMPLETELY screwed up the steering link angle.
That means a lowered steering box or lowered 'Pitman' arm on the box to get that steering link horizontal again.
The more angle off horizontal the steering link is, the more 'Bump Steer' you are going to encounter, and the more leverage you are going to put on the Pitman arm and steering box, and the steering box mounting to the frame.
With road driven vehicles, you want a shorter sidewall tire, with more plies in the side wall.
This keeps the 'SWAY' induced between contact patch and vehicle rim down to a minimum.
When you off road, you want a TALL, SOGGY sidewall on the tire so the tire can deform to the terrain and get traction.
Lifts usually come with wider rims and wider tires.
This aggravates the CAMBER problems, especially when the rims don't have the proper backspacing.
Moving the wider tire out and away from the frame moves the CENTER of the tire/road surface contact patch, and that screws with alignment and scrub radius.
(scrub radius is comes from both tires NOT being turned the same amount when you turn the wheels, one tire 'Scrubs' sideways somewhat, and moving the contact patch around can cause too much scrubbing, steering problems around turns)
Lets not forget things like longer shocks to make up for the increased distance between frame mount and axle,
And longer brake lines, if you use rubber lines, the more rubber, the more swelling, and the more swelling the lower the pressure and slower responding brakes,
When you put on taller tires you are adding leverage to the wheel/tire (Distance between wheel center and road contact patch increases, like putting a 'Breaker Bar' on a socket/bolt)
And the brakes are less efficient since the leverage is working directly against the brakes...
And you raise the center of gravity up which gives that weight leverage over the suspension and contact patch at the road surface...
The suspension being what gives you control over the vehicle and all the stuff that is going on while driving...
It's not as simple as whipping on some lift shackles and some longer, more bowed springs and taking off down the road...