in my opinion the ball bearings, springs caps etc can all be binned. What's important here is that the fluid can return back to the MC, as otherwise your pads will pub the disks (disks callipers need more room to 'return' than drum cylinders). So you need the fluid to be able to go back and forth. When I changed to disks I ditched all those inners you've carefully dismantled. If you have a look at the engineering cross section for later MC's you'll see that it they have none of these gibbons.
And yes, just the front ones that you do