I am no stranger to these GM anti-theft features, but there is an unknown presenting itself on my current project. I have a 2000 Impala LS (3800na) that is getting the engine, transmission, and PCM from a 2000 Buick Regal GS (3800sc). I need to know if the VATS/Passlock relearn procedure will work between the Impala BCM and the Regal PCM. The pinout for the Impala shows the BLUE (C1) plug PIN-15 (TAN) as circuit 800 -- UART Serial Data (unused pin on Regal PCM). The pinout for the Regal shows the BLUE (C1) plug PIN-58 (PURPLE) as circuit 1807 -- CLASS 2 Serial Data.

The differences noted:

2000 Impala LS PCM:
Service Number: 09361735 (CYMZ)
Hardware Number: 09357440 (CYMZ)

Impala PCM BLUE plug PIN-15 (TAN) - UART Data
Impala PCM BLUE plug PIN-58 (BLANK)
Impala PCM BLUE plug PIN-59 (GREEN WIRE) - INFO needed
----
2000 Regal GS PCM:
Service Number: 09380717 (CZZC)
Hardware Number: 09357440 (CZZC)

Regal PCM BLUE plug PIN-15 (BLANK)
Regal PCM BLUE plug PIN-58 (PURPLE) - Serial 2 Data
Regal PCM BLUE plug PIN-59 (BLANK)

I have pinouts from a few different year and model PCM to compare. PIN-58 and PIN-59 show both to be Serial 2 Data on one diagram.
I do not have the exact pinout for either of these 2 cars, but the details of my self-made diagram shows to be accurate and consistent with other PCM units from neighboring vehicles.

What I would like to know is more detail about the VATS relearn procedure between BCM and PCM.
Will this work?
Is a VATS bypass needed? If so, can it be accomplished with a bypass module from an aftermarket vendor?
Is a reflash of the PCM needed?
Will the Impala BCM communicate UART password to the unused pin on the Regal PCM?

Anyone know the answers? Thanks in advance!