Re: 6.0 to 7.3 Conversion
As long as you have the complete donor it will be plug and play. On my Bronco I had to swap out the dash and engine harness along with both fuse box's, but the existing chassis harness and most of the interior plugs worked. Going from one diesel to the next you will probably have a lot less to swap than I did. Dash harness will likely be the same, you may just need to swap the engine harness, which is pretty simple.
As for the dumb transmission, I remember seeing one conversion where the guy cut the transmission hump out of the donor and grafted it into his truck.
1995 7.3 Bronco