So, for IFS, you basically have 4 different options in front.
Spacer lift, which is the cheapest, which also makes it the most popular. Its basically just a puck placed inside the coilovers.
There's the body lift, which personally, doesn't really look all that great on Toyotas. It does get your body a little higher to fit larger tires, but unless completely done, you'll have gaps in your bumper and it'll require a lot more work to get done.
Then you have the coil over lift. Bilstein is the cheaper side (but still very well respected), and you have Camburg, Icon, etc for the more expensive side. Basically, it works about the same as the spacer lift, but the spacer is built into the shocks. (compresses from the bottom instead of the top). The good side is that these shocks are actually made for this, so possibly can get a bit more drop from them and can buy coils that support the weight of your vehicle better.
Then you have long travel, which is basically replacing the guts of the IFS with longer pieces so you get more travel. This is the route the desert racing types like to go, as you get more articulation and softer rides. I dont see there being much use for this for a rock crawler though, as you'd be in it almost as much as with an SAS.
Biggest problem with IFS lifts is the half shaft (CV) angles. After about 3", unless you start repositioning things, you start to run into boot problems on the cv joints. Also, for IFS, you aren't really able to increase the down travel at all (with out long travel), so you're really only pre-loading the coils, giving more height, but also taking away from the amount of down travel you have.
The biggest benefit I've seen from my own IFS (think its the same suspension as yours), is removing the sway bar so both sides aren't linked/restricted based on what the other side is doing. I think I ended up getting a good 1-2 inches extra down travel from that, but of course you do get more body roll on turns.
Not sure what the rear suspension is like on 4runners.
As far as what I've done... The previous owner put on a 2" spacer lift on my truck, which I really cant say I have any complaints of (and if its the same components and want to see how it changes things, I still have the complete coil over assembly you can try and see if you want to run it. If you want to come down to Riverton to pick it up, I'll just give it to you. No clue how much life is left in the shocks though, but they were still good when I took them off a year ago. Some rust.) I moved to Camburg coilovers, which I have set at about 2.75". I plan to go to an SAS after I catch up from paying taxes this year. Real simple to try it out, just 3 bolts on top and 1 on the bottom and the whole coil over assembly comes out. You will want to get an alignment after though.
I'm running 265/75R16 (31-32") now with a 1" wheel adapter in the front to solve some rubbing on the frame, but I'm sure I could get 33's in there no problem. I know people that have run 285/75R16 with just spacer lifts and a bit of rubbing, but not bad. Probably have to pound down the pinch weld near the firewall though. With lots of cutting and tubbing the fenders, 35's are a possibility as well.
Of course this isn't on a 4runner either, but a Tacoma, which I'm pretty sure the 3rd gen 4runners are the same basic parts as a 1st gen Tacoma on the front.
