P.S. box rebuild FirmFeel or Steer & Gear?

The Borgeson units are a new design.
Keep in mind, when the Mopar power steering was first designed and released in the Late 50s, super easy steering was a huge selling point. Their design was aimed to capitalize on that. Cars didn’t have to handle well. Tires were tall and squishy, springs and shocks were soft for a comfortable ride and most guys that wanted handling drove smaller cars with manual steering systems.
In the late 70s, there was some emphasis on improving handling and steering in all American cars. Ma Mopar did integrate their own “Firm Feel” changes to the steering boxes in police and HD applications. The company known as Firm Feel took it further. They do make great products but they are limited in what they can do with these steering boxes.