I have never done this but, I am looking at the 56 manual right now and there are many things they have you do. They have you check the alignment of the steering column tube to make sure it's in line with the steering shaft and it's not binding. You reposition the steering column tube to the under the dash bracket if necessary. You want to have about 1/16 clearance between the steering wheel hub shoulder and the end bell of the steering column. When you got that part finished and the bolts are all tight then they have you go to the steering box, loosen the lock nut,and turn the steering sector shaft thrust adjusting screw in a counter clockwise direction. That is suppose to remove the pre load between the sector shaft and the roller. Next your going to need a spring scale, yes a spring scale that measures in pounds. Turn the steering wheel in one direction to it's limit of travel. Using the spring scale hooked to the steering wheel measure the pull required to keep the steering wheel turning. The worm bearing pre load is satisfactory if the effort is 1/4 to 1/2 pound pull. If the preload is below that, then you need to remove the gaskets (shims) from underneath the steering gear housing and plate. If the measured pre load is higher, you add gaskets until it's in the 1/4 to 1/2 pound pull range.
After your pre load is established , turn the steering wheel from one stop to the other while counting the turns. Turn the steering wheel back half way or to the center position. Turn the sector shaft adjusting screw clockwise until all the end play is removed from the sector shaft. Now your going to check the worm and sector mesh. Using the scale, measure the effort required to turn the wheel to the center position. The final mesh adjustment should be 1 to 2 pounds of pull. If so tighten the lock nut. You should be done.

As I mentioned I have never done this. I hope it helps!