Hi Ron,
If the adjusting screw protudes more than 15mm above the lock nut then no more adjustment is possible and the box will need to be replaced if there is more than 1" play at the steering wheel.
Yes, replacing the engine and subframe mounts are done that way. They really would need to be replaced at the same time, you will notice a great difference when you drive and Paratroop made a great write up with pics in this link
http://www.peachparts.com/shopforum/showthread.php?t=250220 on the procedures step by step. (check your PMs)