expedition builds are by far my favorite build. you have the right idea to a point where you would eant a lift, lockers are a +, and bigger tires. even the bigger gas tank is a good thought. but the approach i would also disagree with. i may repeat what others have also stated to point out the appropriateness of their responses along with my additions:
Tires- make sure you go with a size thats popular cause in the instance where you use your spare and have another flat, youll want a size thats easy to acquire. so in essence, like a wheel that fits that tire.
Lift- pretty much anything with good quality, but, my recommendation is to get the AAL lift(cause its cheaper) and call Alcon springs to build a set of full leafs that will support the weight you will most likely be carrying.
Bumpers/skids- quality bumpers and skids are good for a lot. allows for carrying accessories, winch, tow points, and that sort of thing. also skids will protect the vulnerable points. where as with normal wheeling and what not stock skids do fine, you wont want to take that chance when going across country to a zombie free(or china free) zone.
Lockers- good investment. great return for the intial cost. get through the spots where you normally couldnt with open diffs.
Storage- very important. you need to be able to safely and securely store all that is necessary to survival. both roof racks and internal storage is a must. things that can weather the elements go outside and things that need to stay out of the elements for most of their life to be useful to you go inside. (the list of things to take with you can be SUPER long so dont expect a full list by anyone here).
Motor- keep it simple there too. you dont want something so unique that its hard to find parts for it. if you plan on a diesel swap(which im all for by the way) make sure to use as many stock pars as you can and try to keep the one off parts to a minimum. especially the ones that are prone to breakage. durability and longevity is important, so make sure whatever you would do isnt something that cant take abuse or has a relatively short lifespan.
this is just a quick debrief of the critical points in an expedition build. others can add to this if ive missed any key points. i havent gone to specifics other than any lift and getting alcon springs to make the leafs cause theyre one of the best out there and they make the spring rates to what you specify. therefore wont sag over time and will be less abused in the process. (read more durable)
good luck