Tom: I used a 1970 VW wiring harness for my CMC and, even though I've wired a lot of cars over the years and am not intimidated by it, I wouldn't go that route again - just too much of a PITA. I ended up making several crude diagrams (for different areas of the car) so I could keep the colors straight and all, but I also ran a Stirling fuse/relay block and a few different wires within the harness to either get more circuits (like the tach) or heavier current-carrying capability (like 90 watt headlights) or whatever. In the end, there would have been far less time consumed if I had a correct harness to begin with and only made small mods.
Get a good wiring harness from JPS or VS or IM and put it in, then everything will be the correct length for your lights and gauges, and you won't have to fool around trying to make it all fit. Then it'll all be new and un-corroded and time saved will pay for it in the long run.
Just my 2 cents........Gordon