I have a neighbor who purchased a '46 2-ton with flat bed. His plans are to use it for his business and would like to have it road worthy (interstate/highway) to include disc brakes, replace the 216 with a V8, newer rear axle and automatic transmission. The frame and body of this particular truck is in outstanding condition so he just wants to update it mechanically. What would be the best option for these updates? Entire new frame? Or new axles to replace original?

Everyone here has assisted me immensely with my 48 restoration and am hoping for some more valuable assistance on this '46.
Thanks and have a great weekend.
Jeff