I forgot about this thread. So I have my gauges installed with BIM module. I got the RTX model for my 70 C10. They are awesome. And for my update to the question I asked above, I got everything from the stock PCM/ECM. I ended up with a 2003 6.0L PCM actually, the harness I rebuilt was from a 2005. And I "DO" get oil pressure from the BIM, I also get Trans Temp as well from the 4L60E as well.
FYI I followed LT1SWAP.COM videos to rebuild my harness. It's not that bad to do, you just need to go slow, take notes, and be thorough with the wiring and connections. If I ever do this again, I will extend the harness next time so it would relocate into the cab.
Here is quick video I did a couple months back.
TA_C10 Dakota Digital RTX