It started with an OEM harness converted to stand alone by Wait4Me Performance. Joe repaired their mistakes, extended the leads for mounting the ECM in the interior, built the fuel pump harness, and corrected other problems he found along the way. The entire harness is protected by split-loom convoluted tubing, heat shrink where appropriate, installed a diode at the AC compressor so I won't burn up the switch or car, and installed weather pack connectors where needed. The harness along the chassis has snazzy clips eliminating the need for clamps and self-drilling screws. The F-body diagnostic connector was installed and pinned in the stock location. He married the harness to the aftermarket fuse block. The aftermarket fuse block controls the engine, the OEM block controls the chassis.
I'm competent enough to have installed the stand alone harness myself, but the end result wouldn't have been near as good or detailed as Joe's work. In hindsight, I should have commissioned him to build a scratch-built harness but I'm confident he took care of any weak points he found in the old harness.