Not surprising, the great diversity of answers and solutions.
"ask ten people and get ten opinions"
The 45-70 is my all time most used cartridge and is maybe one of the most adaptable cast bullet round as to both bullet and powder.
Tho it is a little large, it is also my choice as a do all survival rifle here in the Rocky Mountains. Useful ammo can be made using almost any powder and lead you can find.