|Your life will be made 1000X easier if you just pull the evaporator. You don’t need to do anything to the harness if you pull the evaporator.
Remove the glove box and glove box frame, then remove the exaporator. Remove the shield that is covering where the harness comes through. Then just pull harness out with your pinky finger. If a car has no ac, or ac w/o a charger, i like to pull the evaporator. It makes removal and reinstallation take about 5 seconds, vs much longer.
I assume that because it’s an LS swap you don’t have ac anyway. So your ac lines would already be out.