At 3" you'll need longer brake lines, pretty sure there are some in that JY thread I posted above. Should get a track bar to keep the axle centered, but since you're doing a trail beater you may get away with just running it off center. Some XJs would need a transfer case drop, some don't, you can fab some up and save yourself $30. You can still get away with the stock control arms.
Pretty much anything over 3" will require more work/fabrication/money, any combination of these three.