I know its different but, I just completed my a full rebuild on the entire steering in my 54. I was able to disconnect and tear down the box myself. The only time that I was really on my back was when I had to take the pitman arm off my box. I know that a 54 box is strikingly different from the 54 steering, but I know the principles are the same. Once the Pitman arm is taken off, you can start the disassembly of the column. Once you strip that down, unbolt it from the frame and pull it out with the sector shaft. At this point you can put the box with sector shaft on a work bench and take the box apart there.
There are some bearing races inside that have to be pressed out and then new ones pressed in. This is the point where I stopped doing the work myself. I took it to a place local to San Diego called Hilltop Classic Cars. The website sucks but they are quick, honest. If you buy the parts separately and do the tear down yourself, it costs less than $150 for the labor to complete the sandblasting, and rebuild.