So I may eventually fully replace our Jeep with the Montero serving as our all-purpose, go anywhere rig. To do this comfortably I am thinking of ordering the complete OME HD suspension, 2 inch body lift, swapping in the 4.90 gears from a Sport, and possibly the transfer case gears from Mark's if the 4.90 gears don't give me a crawl ratio I'm happy with. Lately we have been spoiled with how smooth and quiet the Montero rides, and I'm thinking that if I do it right it will not mess with the handling and ride quality too much. Tires would be 35x12.50 km2's on 17's more than likely to limit sidewall flex on the street.

What do you guys think, am I missing anything?

Sounds right to me, once on 35's stay away from shaved bumpstops and you're good to go for a long long time. Once you do your body lift you can move the gas tank up 4", this is a great thing to do.

Any plans to run the Sierra Challenge in the future?

Yeah, I definitely have no plans to run shaved bump stops, that's how most guys start busting CV shafts it seems. I have read a bit on raising the tank, at 24 gallons and being low already it makes a big target for rocks. The plan is to get as much travel out of the rear as possible and I may even run some 5 inch travel coil-overs on the front.

What is the Sierra Challenge?

With a body lift you can raise the shock towers and switch to eyelet/eyelet shocks for better shock options and big flex.

Sierra Nevada Challenge
Next one is september 2015

Aren't the upper mounts welded to the frame? I know I can run shock stem eliminators in the factory location and run a standard loop to loop shock, but how/where can you mount new upper mounts?

Cut and re-weld.

That's how I did mine, there's a write up on here somewhere. I tried a bunch of different things and that's what worked, been running the raised towers and long shocks for a few years now and it's been great.

I have the OME suspension on my 98 with 33's and it still rides like a caddy

I can't imagine that a BL and 35's on 17's would change that.

I didn't think Mark's gears would fit the Gen 2.5

You could also swap to a Jeep AW4 tailhousing and run an NP231 or NP242. Stock they are 2.73:1.

Or get lucky and find a Rubicon transfer case. Or a Dana 300 and get some lo--crawler gears at 4:1. That's what I have, just waiting on the $$$ for the gears. And find TOASTY's thread about raising the shock mounts. Awesome flex on the RTI ramp.