These kinds of things are GREAT for rotation, but not so great for daily use too (because you have to take out all of the cans on top or bottom to get to a different one in the row). Now, if truly for emergency storage, not an issue, but like you said, cans come in different sizes, even for the same oz cans. So you're best off going with some kind of rack that has a little wiggle room.
Though, unless the wall is moving, not sure why you'd need the added security of the rack holding them, vs. just on shelves. Could just get a couple or a few of those DVD type holder shelves and adjust the height of shelves for cans, and it'd be easier and cheaper, for your closet. (and easier to have a mix of foods).
For food storage, pretty sure most here agree that you should really only stock what you actually eat. You don't want to change your diet drastically, due to an emergency.
While canned foods are great, and last a long time, home canned items last much longer. (But, that's a bit to get into).
Additional storage options are to get some food grade buckets that seal, and store things like dry rice, beans, pasta, cereal, mashed potato flakes, corn, etc. as these will keep for about 2 decades, if properly stored.
Packaged survival food can be good, but it is prohibitively expensive for how much you'd need. (and it's not what you're already used to).
