Update, I called Rhode Island Wire today, to ask if they would sell me some of that braided loom. They told me that it was woven on to the harnesses by machine after the harness is put together. So, it looks like I'm going to go another route. I guess if there's not an original truck parked next to mine, no one will be the wiser.
I did buy some fabric braid insulated wire from them for some harness repairs. The lady I talked with was very knowledgeable, trying to say that the wire I wanted wasn't correct, but she thought I was still talking about the Starter to ammeter wire harness. She was OK with my purchase when I told her it wasn't for that harness, but to replace a bit of wire on the main harness.
