Need advise LS swap

[Homebuilt Hotrods]

I have a 2003 4.8 ls engine with 90k miles on it. It has the harness factory to the engine with the green/blue plugs. It is drive by wire. I do not have the pedal or module for the dbw. The trans part of the harness appears to be a dual plug for the neutral safety switch.

Computer is a 2003 6.0 express van with drive by cable which I plan to swap to. I'm told this computer was the one I need to use green/blue plug and run the stepper motor on the drive by cable throttle body.

trans is a 2002 4l60e 2wd from a 5.3 engine has a single plug for neutral safety switch.

I am looking for a recommendations on who to use to rework my harness and reflash my ecu in a timely manor.

I would like to reuse my own harness as I know it fits my engine with the included changes. Thank you for any advise.