One way 6:1, the other way half a dozen to 1.

You should be able to make it work, most people that want a heavier duty setup just go with the Toyota Mini Pickup setup, or a Tracker/Sidekick.
New mounts will have to be fabbed up. A new turnbuckle setup to connect your existing steering to the new box. Then splice your steering bar together, so your existing setup will have the correct ball joints at both ends. Alternatively you can put a new end on the Pitman arm.
Make sure you will have proper clearance, you might need to reposition the box depending on how much travel the arm has.
Your probably doing a custom solution, but you might try checking out Trail Tough's selection of steering components. They have some kits available for running Toy hardware on your Samurai.
http://www.trailtough.com/steering_components.htm