How to convert a 1963 lemans/tempest from manual to power steering.. Factory method or cut shaft.

A steering box change will likely be required and the Pitman arm will also change.  A quick look at the 1963 Lemans Tempest Factory Assembly Manual would show you how they did it and provide the part numbers.

You might consider using a modern 1995-98 Jeep Grand Cherokee (JGC) power steering gear box - this might work but will need a bolt hole comparison. This gets you a stiffer torsion bar force and a modern vehicle steering ratio for a much better road contact feeling. I'm putting this into my 70 Catalina. I will reuse my Pitman arm and it requires a Dorman 31011 rag joint to adapt to the 1970 steering shaft. Reuse the JGC low pressure hose from the junk yard.  A hose adapter on the high pressure side or a custom hose completes the job.  

Basically, Jeep purchased Saginaw steering gear boxes from GM for less money than they could produce them in house.

Rick