[Brian]

Brake drums not cracked, they are nos
Residual valves? Why? isn't the residual valve built into the m/c? And, having the remote reservoir mounted up on the firewall actually adds a slight 'head'.
Brake cylinders made wrong? Yes, I am convinced these w/c's are wrong. Only way I can bleed all air out, is to unbolt from back plates, whilst still attached to hoses, G clamp across ends of cylinders to prevent pistons popping out, and 'manipulating' them into such a position as to get all air out. Re-assemble everything, still good. Drive the 'beast' and upon first application of brakes, pedal goes to floor!
Single circuit, Lockheed style m/c with 1 1/16 bore.
Why 1/4" lines? Dunno, ask Henry Ford.
Speed bleeders could be a bit hard to get out of the USA right now, I have, during all my efforts, wrapped thread tape around the threads of all the bleed nipples.
39 Lincoln brakes
Yes, have set all shoes hard out against drums and set handbrake, and had good hard, high pedal. Then, when I drive this thing and apply brakes, pedal goes to floor. Repeated pumping brings about a spongy pedal that still goes to floor.
Much angst!!