Thank you! It's a real cheap route too! I probably only have a couple bucks in thread and I still have enough to do a hundred more cars probably. I like the way it's held up too, when everything's on, the wires pretty much disappear. I also used the same method on the headlight, taillight and every other grouping of wires that you can see.
The thread looks pretty cool, but why not try aircraft style lacing cord? It's super durable, easy to do, and has been in use since who knows how long! Most likely returning WW2 vets would have been familiar with and used this method. The lacing cord is basically a woven, wax coated string. Pretty similar to that stuff sold with the "leather sewing kits" that have a thick needle and big wooden handle. Anyhow, here's a link how to do it: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%2043.13-1B/$FILE/Chapter%2011.pdf By the way, the AC 43.13-1B is a wealth of knowledge for all sorts of things mechanical and it's free on the FAA website.
I did mine with the same look of thirty7slammed and used Moroso 7mm wires, somebody's urethane clips. Same header appearance over the wires. Second set of wires because I didn't pay close enough attention to how I twisted the wires to make it all look clean and fit well at the time of all parts of the engine and surrounding being cold. Neat pile of wire separators are replaced along with the first set of plug wires. Cheap *** zip ties tidy up and hold the newer wires down with plug wire twist to make them conform to clearance areas again. So far, no problems yet.
These things. To my eye it looks like someone built a shelf to lay the wires on. These were not around in the 50s,60s. Oh and I just love the color of the plug wires. Plug wires are supposed to be black or fabric covered. Not pink, blue or those gawdalful yellow Accel wires from the 70s. I'm more inclined to run them close to how the factory did. I used to pocket all the little black plastic wire holders on all the Chevy engines in the junk yards. Now they are readily available in the Chevy parts houses. And no I don't want these in blue with a company logo on them either. I'm such a grouchy opinionated old fool.