[RichardJ]

Before you take all that info as fact, there are things you should think about.

>>The amount of fluid that a drum brake master has to move is less than disc brake<<
Think of that from the perspective that the drum master and the disc master are in the same unit as opposed to a drum/drum or disc/disc MC.

The volume of a cylinder = πr²h (That's supposed to be PI).
On ALL dual master cylinders, the forward piston is called the Secondary Piston and the rear piston is the Primary Piston. The fluid in the Primary Chamber, pushes the Secondary Piston forward until the Secondary Chamber compresses and begins to develop pressure. The primary chamber begins to develop pressure at the same time.
Both the Primary and Secondary pistons move forward the same distance at the same time.

The Diameter (and Radius) is the same for both the Primary and Secondary pistons, so the same volume exits both the front and rear ports and it is under the same pressure.

>>Drum brake masters have 10 lb residual valves at the outlet<<
I think you will find that very few new and rebuilt master cylinders have a residual valve because the cup spreaders have been improved and do a better job of keeping the air from entering.

>>Can I use my manual master on a booster? - Yes<<

There is something they are not considering. If your foot moves the manual master pistons forward a 1/2 inch, the pistons move a specific volume and produce some specific pressure.
If you place a vacuum booster between your foot and the MC pistons and your foot moves that same 1/2 inch, the booster will only move the pistons about 7/16 inch. The action of the booster looses distance.
This is why a MC used with a booster usually has a larger bore. The piston in the larger bore doesn't have to move as far to move the same volume and then produce the same brake line pressure.
The same braking with less foot pressure.

In your video, you are holding a old MC which you describe as being a power MC. It looks like it has a rubber dust boot on it. Rubber boots are used on manual master cylinder to keep dirt away from the exposed piston. The boots don't fit between the MC and the booster.
You should have a boot on your new manual MC.
Your questions about large and small reservoir sizes should be answered by looking at the single reservoir on the MC mounted on your truck. It doesn't matter the reservoir size as long as you don't run out of fluid when the disc pads wear down.
Drum brakes with self adjusters never have an issue with small reservoirs.