Here is my ideas to keep the speedo and cruise working. I have a 95 Tahoe 4wd and want it to function. seeings how nobody one the face of this planet can tell me exactly what to do to mate the ls harness to run them, ive put together some theories.

Option 1. Leave the factory harness and pcm in the truck. To my knowledge the only thing engine side I need is TPS signal for the transmission to function. splice the ls and TPI engines tps sensors together and trans should work.

Option 2. use an ls harness to control the trans and splice the tahoes factory VSS sensor into the ls VSS wiring and the tahoes ECM should read that and the speedo and cruise should work.

Im not sure what part of the factory ecm sends signal to the dash but I have read of all kinds of screwed up signal issues and speedometers not working.
But here is my understanding on how this work. PLEASE correct me if im wrong.

VSS sends signal to tahoes ECM, it then converts that into whatever it needs and outputs it to the speedometer and the cruise control module. SO instead of bypassing the factory ecm why cant I just send the proper signal to the ecm so it can do its thing.
Either by sending it VSS signal or by sending it TPS signal and letting it control the 4l60?

I hope I am making sense out of this.