All the components prior to installing the rear tires are in place, but when attempting to spin/rotate the tire this won’t happen, it is very tight.
The brake cylinder is new and all the brake shoes have new lining; the thickness, width and length are to specifications outlined on the shop manual, the thickness is 5/16. The inside diameter of the hub is 15 inches. According to the mechanic, the adjustment can’t go any further.
I noticed by looking at the pictures, that the primary shoe is facing backwards, and the secondary shoe is facing forward; this is the opposite of what the description in the shop manual.
I will definitely make these changes, but if this is what is causing it, why?
Any other things I need to look out for?

 

When I reassembled mine after replacing the wheel cylinders, I started with all four adjusters in their "loosest" position. The cams on the upper adjusters need to be turned so they're at their lowest point where they touch the shoe. This is just shy of their highest point.

I can see your cams in the top pic before you painted, but I can't see them in the after pics. The left one in the top pic is adjusted about half way out.

The lower adjusters are also cams, and need to be turned to their lowest point to start.

When you put the drum back on, it should be almost sloppy loose with those adjusters all the way down. I then adjusted them one at a time, starting with the top, until the drum wouldn't turn, then backed off a hair. Then repeat with the other three.

And you're right, the primary shoe goes to the front. That might be your problem, but I doubt it.