I just reread the this entire thread, including the title "What am I doing wrong?"
Short answer is: You should have replaced the read wheel cylinders if you thought that they were original.
That is the first rule in Old Truck Repair 101.
All is well. You got it figured out and maybe someone was entertained by us chasing our own tails for quite a while. smile
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission