Early Ford Hydraulic brakes in 1931 Fordor

[Sparta]

Hello everyone! I recently sold my 31 Tudor for instead a 31 Fordor. Love the car. It has a few subtle upgrades for drivability, one of them being hydraulic brakes from an early ford car.

I’m having problems with it. The previous owner installed everything just before I bought the car, and had a health scare so sold it before buttoning things up. It has brand new wheel cylinders, master cylinder, shoes, drums, and hardware. Despite this, every time you press the brake pedal down it is spongy and goes to the floor. Pumping it makes no difference. Heres what I’ve tried..

starting with rear passenger and ending with front driver wheel cylinder, I’ve tried…
Pressure bleeding from master cylinder with custom made pressure bleeder.
Vacuum bleeding from wheel cylinders.
Conventional two man pump and bleed.
Adjusting shoes to make sure they barely drag wheel.
Double checked the master cylinder rod adjustment.

The master cylinder is under floorboard and close to same height as wheel cylinders, which all sit at the top of the backing plates. After all this I still have very little brake pressure. Pumping makes no difference, and if driving at 20 mph, slamming the brake pedal brings you to a very steady stop. Any ideas? Thanks!