You will likely need a disc booster. Pic in post 2 looks like a single diaphragm drum booster. The travel is different between the single diaphragm drum boosters and the dual diaphragm disc boosters. That’s how the factory did it. Some folks say the drum booster works on a disc setup, ymmv.
It does state its for disk brakes so that's a little reassuring , or both as it states drum or disk ? Of course it states 10" rear drum , got to check that as well since I upgraded to 8 3/4 rear as I am unsure