Is there a compelling reason to change the original I beam axle suspension to a M-II? With a thorough rebuild, there's nothing wrong with the straight axle, and if you want to have power steering, an electric steering assist such as a Prius or other modern vehicle uses can be adapted without any modification to the basic suspension system. A front disc brake conversion can also be added for better stopping capabilities, also without modifying the basic steering and suspension system. The less you deviate from the original design, the more likely it will be to get past the inspectors. Good luck!
Jerry