If you can pump the brakes up with the pedal, then you still have air in the system.
I don't know if a 52 2ton came with a hydrovac. Mine is a 57 2ton GMC. Had to buy a new hydrovac. It has 2 bleeders on it. Also mine has 2 wheel cylinders per wheel, that have to be bled.
Did you bench bleed the master cyl.?

57 GMC LCF 370
55 John Deere 40-W
59 John Deere 430-W
2000 GMC 4x4
56 John Deere 420-W
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