Thanks for the input that you guys gave regarding potentially cutting the LT1 harness. I didn't end up needing to cut the harness and instead was able to feed it through the backside out into the engine bay.
Here are a few pics of the way that I ran the harness for the lighting, horns etc and then also the way that the LT1 ECU is mounted:
Wiper Valence area with airbox removed:
Wires feed through the firewall here (harness on left goes to the LT1 harness, harness on right is lighting, etc)
Lighting wires lead into the air vent tubes and then out a grommet towards the front of the car.
From there they go into the side of the base of the radiator support and out the other side:
In the middle, the wires for the cooling fan and horns come out nicely (since the pic, they have been grommetted and covered:
Here are pics of the ECU mounted (the ECU is mounted using part of the factory mount and several spacers to lift it up off the metal:
Currently, the wiring is being cleaned up where the harness exits the firewall. Due to moving the harness closer, I now have a good foot of extra harness that's taking up a lot of space. There is just enough space for all of the relays, etc. to fit and be covered up! Nice and clean.
Thoughts?
Bryan