From what I have read, it is ideal to keep the drive shaft angle to 2° or less.
There really isn't any room the move the transmission form left to right so you are stuck with whatever you get. I worked out the trigonometry and found that you have a 2-inch margin or error (left to right) if you want to keep the DS angle under 2°. From visual inspection, it looks to be within that window.
Generally, all you need to do is align the bottom of the transmission mount with the floor pan (as allotted by the typical transmission member architecture). For better accuracy, use an angle finder ($10 at sears) to align the shaft vertically. There is a ledge on the T56 that you can use to reference the angle of the output shaft (see below).
If you have a drive-shaft, install it and measure the angle. If not, use strait piece of metal or wood and place it from the center of the output shaft to the center of the rear-end flange.
Created by EyeOutThere