We did a stop in Danville with the Collings bombers and got to go through their restoration shop. They had a Mustang there at the time getting a stock restoration, authentic as possible including armor plates. He explained that it was no longer possible to get the original wire, cloth insulation IIRC, so what they did was have wire made to match original wire in dimension and color. This was done for wiring that would not be seen except by someone working on the airplane. Many restorations today are as authentic as is possible. Big salute to the guys doing the work and the guys willing to foot the bill for that level of detail.