Two ways to go on that, buy stock lengths, for like my 350 engine, supposed to run down lo, and I have headers, so up/over, shorten as needed 8mm wires, Jacobs ceramic boots....HEI......
OR just buy a length of wire, and clips/boots and DIY......I have done both ways, and the last go round, I just modified some 'stock' wires and used the Jacobs ceramic boots.....:amazed:
So I ended up buying an Accel custom length kit. Was thinking about running the wires under the headers but there is not much space there so it looks like clipped onto the valve cover bolts is my easiest/best option.
Finally got this done. I used Accell cut to fit wires with ceramic boots. The only difficulty I had is that the ceramic shield around the spark plug boots won't allow the rubber expand when you are pushing these on the plugs. They are really difficult to push on and almost impossible to get off. Even with dielectric grease.