In regards to the sodium content, it seems equivalent or slightly lower than most canned goods. It wouldn't be a sensible diet during regular times. However, I think that in a survial situation eating with that much sodium is better than not eating at all.

In the 80's and 90's I was concerned about sodium intake and my blood pressure. There are quite a few products (soups, vegetables) that are canned with less sodium. Also, foods like oatmeal, rice and pasta usually don't have a lot of sodium in them (it's usually the sauces that load up on it).

I haven't seen any freeze-dried or dehydrated conterparts. Do you have space for a garden? I'm assuming that you're keeping this food around for a "dig in" situation. Keeping a small garden, and a store of non-hybrid seeds, may be another option for supplimenting your diet.