Never done this before.... but since you are wanting to do the swap, the easiest would be to find a COMPLETE 7.3PSD doner truck. You will need the engine, the PSD wiring, the instrument cluster and all the wiring (since the PSD only came in the OBS body, and you have a Bricknose, some have changed the entire dash, since the instrument clusters do not directly swap). PCM, and I am sure there are some things that I am missing.
One other 7.3PSD option would find the T444E flavor in an IH (Navistar) medium duty truck. The PCM is self contained and mounted to the rocker cover in these, instead of integrated into the truck like in the Pickups.
In all honesty, if you are wanting this truck to run again, it would be easier to rebuild, or find a good replacement IDI and drop it back in. The only thing the 7.3IDI and 7.3PSD share is engine displacement. Baring a select few parts, nothing in the 2 engines are the same......