3B - the cylinders fit just fine. I'm still buttoning things up and need to bleed the system.

I'm still confused on the wheel cylinder activating pins being on an angle - wheel cylinders of course had no effect. The pictures in the shop service manual do show them being on a slight angle. Also, the action of the brake shoe centering can take them on an upward angle depending on which way the shoes need to move. The activating pins are designed to meet the cylinder piston on an angle. I do have to admit my angle looks excessive. I would be very interested if someone could find a good picture of the mounted brake shoes on a 53 or 54 1 1/2 ton or 2 ton truck. I scoured the internet and found nada.

As far as I can tell from the shoes, they are most likely Chevrolet 3723922 which was the recommended substitute for the original 3703510. I found a picture of the 3723922 on line, and they look identical to what is mounted on my front brakes.

I'll post back as to how this all works out.......