You'll probably want 1.75" worth of bump stop spacers up front and probably around 1.5 - 1.75" out back. Might need a little more than that. I know I did and I'm running almost the same size tire.
I have almost the same set up as you: 2.5" lift springs, OME 2" lift shocks (N66 and N67s's), and 33x10.50's on my stock Canyon rims with the Spidertrax wheel spacers. With the wheel spacers I get 4.25" of back spacing. I also have a 1" body lift installed. Even with the BL I still needed that much bump stop spacing to keep the tires completely off the fenders.
You might think this is a ridiculous amount of spacing but I can tell you that after doing this I am (metaphorically) beating my head against the wall for not having done it before. No more ugly, gut wrenching "POP! POP! POP! Bbpbpbpbbpbp!!" sound from my tires shreading themselves and the fenders. But most importantly, the Jeep rides so much better on the trails.
Without the bump stops it turns out my shocks were bottoming out and acting as the bump stop. So when I'd reach the limit of up travel I'd get a hard bump if my tires didn't hit the fenders first. With the bump stops I don't feel that hard jolt any more and the Jeep feels much smoother when the trail gets really rough and the suspension is flexing out like mad.
If you wish to verify how much bump stop spacing you'll need it'll take maybe an hour+ of your time. And another 1-2 hrs + shopping time for the bumpstops. The procedure looks like this:
Step 1 - Removing Stuff
Get your rig ready for measuring by jacking up the front and removing any springs or other items that put load on the suspension. Jack up your Jeep and remove the tires, disconnect the lower swaybar end link, and remove the spring. Also, be sure to removed the foam bump stops themselves. These will compress all the way and shouldn't be factored in to any bump stop spacer calculations. You'll be measure from steel tot steel contact points. It may be helpful to remove the shock but you'll want to have the shock connected as you'll want to keep the shock from bottoming out in addition to keeping the tire from rubbing your fenders.
Prepping Jeep for bump stop measuring.
Step 2 - Flex it Out
Next, put the tires back on and start flexing out the suspension with your floor jack. Remember, the springs are out and the sway bar is disconnected so the axle will freely move. Be sure to turn the steering wheel back and forth with the tire stuffed to make sure it clears. Give yourself about an extra 1/2" between the tire and fender.
Flex out the suspension with the tires reinstalled.
When properly bumpstopped, the tire can turn through
it's entire steering travel fully stuffed without rubbing
anything. So, does it look like I'm really loosing that
much up travel with so much bump stoppage?
Step 3 - Measure
With the tire "fully stuffed" plus 1/2" for clearance it's time to measure the distance between the bump stop retention cup and the steel contact plate on the axle that the bumpstop hits. This is how much bumpstop you will need. Double check to make sure your shock does not bottom out before you reach the upper limit of travel. This helps to protect and preserve the shocks.
I was shocked (pardon the pun) to learn just how much bump stop spacing I would need on my rig. At first I was a little frustrated and thought "so much for my 2 1/2" lift." But then I realized I wasn't losing any uptravel since the tire would have hit the fender anyways. This way, I don't really lose any practical up travel and I protect everything: shocks, tire tread, and fenders.
Yes, you'll need a lot of bump stop. 1.75" for me in this case.
Measure from steel-to-steel as the foam bumpstop will FULLY
compress under load.
Step 4 - The Bump Stops
At this point you can either fab up your own bump stops or buy something commercially available. Being cheap, I opted to fab up my own. First, I got some counter sunk allen bolts the exact length I needed in the largest size I could get. In my case: 3/8" dia x 1.75" long. Next I picked up a scrap of 2" schd. 40 conduit from the plumbing / electrical supplier. The guys at the shop were nice enough to cut it to length for me for free on their machines. This saved a lot of time and got everything squared off. Then I drilled a hole in a piece of scrap 1/4" plate steel and counter sunk that. This is to be the top of the bump stop and the plate needed to be large enough to fit the conduit. The schd. 40 sections were dressed up a bit and the galvanizing ground off in preparation for welding. Next the plate was centered over the conduit and the two welded together, then painted when cooled off. On the axle I welded a nut to the axle bump stop contact plates. It was easier than drilling and threading a hole.
That's it.
When you go to re-install the spring you'll need to slip the bumpstop and the new bumpstop spacer in side the spring coils. Push the bump stop back into the retaining up. And slip in an allen wrench and bolt the spacer down to the axle.
The parts needed for fabbing up your own bumpstop.
Bumpstops ready for painting.
The nut welded to the axle plate.
The whole thing reassembled with the new bump stop spacer.