[C.I.Blazer]

I am working on wiring my PSI harness and had some questions on how to wire the NSS and my back-up lights. I did my best to research and wanted to confirm some of the information I found. The swap is an LQ4 and 4L65E from a 2004 Yukon Denali and I am wiring with a PSI Harness.

The car is a 1971 Blazer. It was originally a 4speed that was converted to a TH350 at some point. The wiring is a total mess and I am slowly working to clean it up. The old transmission had a floor shifter and I am using a Gennie Shifter on the new one. The shifter has a simple NSS contact switch on it. I believe I have found the original NSS switch (jumpered switch with purple wires) and the the backup lights (light and dark green wires) under the dash (see pic below).

I understand the NSS is not required for the PCM but helps adjust idle when in park and neutral and I would like to hook it up. So, my plan is as follows:

1) Connect the PSI harness wire to one side of the NSS on the shifter and a wire to ground to the other side. This would give a ground signal to the PCM when in park & neutral which I believe is correct.

2) Use the PRNDL switch on the transmission to drive two relays. One would serve as a NSS that would only allow the car to start in drive or neutral. This would essentially replace the jumpered mess in the picture. The other would drive the reverse lights when in reverse. I have the large style switch on the transmission and while I do not know (yet) how to wire this up, I believe this is doable. Can anyone confirm?

3) My other option would be to run the wire to the starter through the NSS on the shifter and get the PCM NSS switch from the PRNDL switch. Not sure if one option is better than the other. Any advise?

Feeling a bit overwhelmed by this wiring phase, but like this whole process it is fun to dive in an slowly figure it out one step at a time. Couldn't do it without this forum. Thanks for the help.