You can shim up your tail stock by placing a .010" shim between the base and the upper portion of your tail stock to reduce some of the wear you have indicated that exists. Don't mess with the headstock alignment. The headstock should be aligned properly when it left the factory years...
The inside mikes you have are interchangeable with those made by Starrett tools, at least the handle and wrenches are, and would make good replacements.
This part of the Lufkin tool line has not been produced since the late 60's.
If you are in the Houston Texas area, Brown Book store usually has API RP7G specification in stock. It's very pricy!
The simpliest way to calculate the joint strength of any pin rotary shoulder connection is as follows: If the pin relief groove is used calculate the cross sectional area...
