I'm working on a 65 Dart for my wife, and am going to convert from manual to power steering.
After reading all the posts about people wanting to switch from power to manual steering, because of the issues they have had with the stock power steering system, I've decided to go the Borgeson converion box route.
Borgeson makes a power steering conversion box. It is basically a modern Jeep power steering box, that has been modified to fit on older cars. They make kits for a number of older cars.
After I decided to go this route, I looked around on the forum, and am surprised I havn't seen much talk of them.