Mounted the 99.9% finished harness in the engine bay tonight. Have to modify the hole a little bit so the plug fits, but I'm happy with the results:
Here's a shitty photo I tried to take of how I routed my wires:
Yeah, I just noticed that ground too. Once I have my transmission installed again I will have the starter harness in there as well. But that's all you will see as far as engine bay wires.