When talking 'survival reloading', I assume you mean getting the most shots out of the least powder, lead alloy, and primers. A round ball has some favorable characteristics in this case. A ball takes the least amount of lead to fill a barrel, to seal the bore. A round ball will also 'resize' itself to a slightly smaller bore more easily than a long slab sided bullet, if you don't have the facilities to resize. I have seen rings of lead cut from round balls forced into pistol cartridges by hand.
The powder I'd use would be Bullseye. Yes you have to be careful, no argument about it. You get more shots out of a 1 pound (7000 grain) can than anything else. Using BP would always be an option. I would rather use home made BP than home made, nitrocellulose powder. The treatment of of guncotton made with mixed nitric and sulfuric acid is beyond most, and the follow up treatment to convert the guncotton to a safe gunpowder is beyond anything a non professional could attempt. Yes the formulas and procedures are out there, but even simple powders like cordite are far too complicated. Straight guncotton will ruin your gun, it is way too fast to use as a propellant. Wet guncotton was used as a filler for naval mines, to give you an idea of how fast it is.
As it stands, you will be limited to how many primers you have. I don't know of any standard, reliable, or published ways to reload a primer. Primers have been the subject of many improvements. They have removed the mercury that used to be in primers, which is healthier for you and your used brass. They have removed the chlorates and perchlorates that made the chloride residue that would rust a barrel overnight. The standards and material used now would be hard to duplicate, even though the primer is of simple construction. I'm sure it could be done with a little experimentation, and acceptance of 'corrosive' priming. I remember once seeing an article on reloading 22 LR. I wish I had saved it, just for the information. Anybody else remember that?
Maybe a flintlock or matchlock would be the ideal survival weapon?

22 LR are looking better, as bang per buck.