I guess your list of needs would depend on what sort of off-roading you plan to do. Stock jeeps handle a majority of roads just fine. Are you looking to rock crawl? Sand dunes? Mudding? Jeep trails? How seriously? Is this ride a daily driver that needs to go on the interstate? If so, 2.5L will be a turtle pushing too large tires. Large tires require lift, steering & suspension upgrades, gear mods, axle upgrades and even brake upgrades.
It wouldnt hurt to test drive some modified jeeps to see what you like or dislike about their setup and handling. Then apply it to your personnel needs on the trail.