...got some minor disassembly done - now it's time to figure out how to make everything fit the way I want...
another thing I did before taking it all apart (and thanks Ed for the idea) was to conduct a 'test' to try to determine a bit more about what the PCM actually controls, and I like what I found out. While the truck was still intact - before I disconnected all of the wiring and separated the chassis - I turned the key to [run] and confirmed all of the interior functions like the HVAC/blend doors, radio, turn signals/lights, windows and locks, mirrors, etc, all functioned normally - including bumping the starter, which they did. Then, I disconnected the three big terminals at the PCM and ran the test again 'PCM-less', and all of the interior systems (including the 'start' circuit) functioned as before. I couldn't confirm whether the A/C functioned normally but I can get around that.
So...other than the A/C, it appears I will no longer need the PCM - at all, which is good because I didn't want it in there in the first place. There is another computer under the dash - can't recall the exact name for it - but I'll continue to need it for the interior functionality and that's fine. All I'll need is separate sub-stations for solid B+ and 12v-switched power and grounds, and all of the new driveline systems (EFI, sensors, gauges, etc) will function normally.
Anyway, I'd long been wondering whether I'd still 'need' the PCM for anything after the driveline swap, and apparently the answer is 'no', and I thought that was worth mentioning.