That's a good starting point. How much additional weight are you planning on? i.e. bumpers, racks, winches, coolers, ect. That will help narrow if you need a beefier 2.5" diameter suspension set-up or if you will be fine with a 2.0" diameter set-up.
What size & type of tire do you plan on running, will the wheels be bigger (i.e. larger diameter or wider) than factory as well? Do you plan on running trails at a quicker pace or slower crawl?
The better idea you have of the vehicle use/loadout, the better you can plan what the vehicle will need. Because honestly if you're just gonna keep it mostly stock save for 33's and you're not gonna wheel it that hard or overload it for trips; 5100's with a spacer isn't a bad starting point.
But if you're planning on a front bumper, skid plates, 34" or 35" tires, sleeping platform with cooler, ect. then you'll want 2.5" diameter coilover suspension and a set-up that will better compliment the vehicle's build.
It's all about context. For example, I never really planned on 35's originally (it was wishful thinking more than anything else when I first bought the 4th gen). But I knew I wanted skid plates, full metal front bumper, and other stuff. So I saved up and invested in my OLW 2.5" Coilover set-up (made by Radflo), the 700lbs springs are stiffer than most kits (usually I see 600~650lbs offered) but better compliment the front bumper and extra weight from the skids. The front and rear shocks are 2.5" diameter and the kit nets me about 3" of suspension lift. That was the second mod I made to the vehicle before putting 33" tires on it (the first being the bumper), but the only modification I have made to the suspension has been new UCAs (from my recent run in with a log on the trail) to replace my old SPC ones and gusseting the spindles since I was replacing stuff anyways and I wanted to strengthen the front for the 35's better.
It was an expensive set-up (I think the kit with SPC UCAs came out around $2400 in just parts), but the suspension has done me great and let me focus on loading up the 4Runner with the stuff I want to do without having to second guess if I am straining the suspension. If I had gone with say 5100's or a spacer lift I would have easily blown my shocks by now if not bent them (based on how I drive the vehicle and how heavy she's gotten) and I would be spending $2400 on top of the initial probably $600~700-ish I spent on the more affordable lift.
It's all about planning, I was just explaining this to a coworker who's thinking of getting a 5th gen he may lightly off-road. I told him the same thing, "drive it, get used to it off-road and decide what you're gonna do with the vehicle; once you have that in mind planning out a build is easier."
Not trying to beat you up on this, but this is a case where "measure twice, cut once" is honestly a better approach. It may be more beneficial in the long run to save up for a proper coilover set-up if you're gonna really use the vehicle vs. having to replace a more affordable lift later down the line because your mods outgrow it or you break it.
