John,
I just read an article in Custom Classic Trucks about just such an upgrade. The only difference is that truck was a '56. One problem they pointed out is that if you hooked up the apparent rear brake line to the rear chamber of the master cylinder and the front chamber to the apparent front brake line then the truck pulled hard to the left. The reason for this, they discovered, was that the original brake plumbing takes a line to the left front brake and the other line, that appears to be the rear line, runs to a "T" on the right side of the frame and is attached to the rear brakes and the right front brake. I checked my factory assembly manual, (sect. 5 sheet 6.00), and it appears that the '54's are plumbed the same way. So, to get it right you'll have to re-plumb the front lines together and cap off the part of the "T" that would run to the right front brake. That way you’ll have two brakes on each chamber instead of one on one and three on the other. Good luck with it.
