converting manual steering to power steering

Is this going to be hard to source out parts to convert my car to power steering? Real bad rotator cuffs on both shoulders are the blame for wanting to do this.
Trying to figure out what years of Valiants and Darts work best for the correct steering column to replace the column without doing any modifications. I know I will need a new steering box, might as well pop a new pitman arm on it at the same time. I want to start sourcing out parts cars so any advice would be greatly appreciated.