Hello everyone. I'm new to the site, and don't have any auto repair experience. I'm kinda diving in blind into the hobby, and might be asking a lot of dumb questions, so I hope you'll have patience with me. I purchased a 1951 Dodge Coronet with the Gyromatic transmission. It's been sitting in a barn since about 1984, 25,000 original miles. Interior is in pretty sad shape. It starts, runs and stops, but almost ALL the wiring insulation has been eaten by mice. A lot of the electrical things aren't working on it, and I hope most of that is due to the wiring being bad. The battery drains overnight while parked, so I know I have at least one major short somewhere. Breaks are ok, manual shifting works, but I'm not hearing the "Click" or "Clunk" for the Gyromatic. Running lights, horn, and the heater motor work, but the headlights, interior lights, panel lights, and the windshield wipers aren't working. One thing I can't seem to find a consensus on is what gauge wiring to buy. I found an online store that sells cloth covered wire for about a buck a foot.
https://enginebarn.myshopify.com/search?q=Cloth+Covered+Wire&x=0&y=0
Some people have told me that for the best performance I should use 10 gauge for everything on these old 6V positive ground systems, but I worry about not having enough room for the wires to fit through the firewall. I have a service manual on order, but I'd like to buy the wire now so I have it ready when the manual comes. Any recommendations or tips about the wiring?