I don't think the KJ front suspension and steering is up to the task of running 33's or larger any more than the front diff is. I think All of it needs to be gutted and replaced.
Don't give up on modding an IFS system out of a different vehicle to work w/ the KJ if that is what You want. Start finding different vehicles and taking measurements. I would bet that the IFS set up out of another 4x could be adapted to work, maybe by creating a cradle assy/adapter that would bolt up to the KJ. Look at how the KJ's front end bolts up and design an adapter that would replace the whole front suspension And diff assy. Use a Toyota front suspension/diff or similar w/ the adapter and you will have many options for modding it further.
What it Always boils down to is $$. ANYTHING can be made to work if you throw enough cash at it. Somebody will eventually do it IF they feel they can sell enough to make some money on it. Or, it will be done by someone that has some money to throw at it and they are determined to just do it even if only for their vehicle. For the kind of wheeling some want to do, a SFA swap makes good sense because it can be done fairly easily and cheaper than an IFS swap. (right now anyway) The SFA swaps are common on many IFS vehicles and Proven to work well too.
I think the current set ups we have for the KJ are great for a mildly wheeled vehicle. I think the front diff can survive if not overly abused. (just ask allyrand about his front diff which has survived His heavy foot)
I think 31-32" tires are the limit for this set up and if you are having a great time wheeling a rig like that, then leave it be. Set your money or spare parts aside to fix it as you break it. Really not much different than having a mildly modded Wrangler that has axles or control arm mounts, steeering parts, etc. break on it from wheeling. (except there are stronger parts to upgrade to on the Wrangler)
Blah blah blah..... i'll shut up now.
