This video is more realistic way to run the wires. You simply said as you done it, that letting the wires are just kinda slope down for a loose look. In reality all plug wires do hang down from plug to plug!
You would have to research how a cycle is wired and find wire of some sort that's the appropriate scale. I don't build scale cycle kits so I'm not of much help there...
Im a chevy guy so as you know the distributor's are in the back but i am a race car builder. I always make plug wire boots. Does that engine beings the wire go into the top of the valve cover need boots? Just wandering because all i build is race cars. I know all of the real cars i work on on the side to make a few extra bucks are all booted but that seems to be a vintage engine.
Not a bad idea. I don't show my models, they just sit on a shelf so I've not felt the need to dive in to the full detail builds. I barely add plug wires.