Would it be too hot to run under plenum, out of the way?
I was talking to a friend who's trying to repair a Granada Cosworth 24v the other day. Mechanically fine but they apparently ran a loom as thick as your arm down through the valley, down the transmission tunnel on top of the autobox.
Unfortunately they scrimped on the insulation, a coolant hose went, which necessitated access to the valley area, and as soon as the loom was disturbed the thing went haywire.
Turns out the whole lot had turned to powder. Moreover, the damage extended far enough down the tunnel that it was impossible to splice in a new section from above. The loom terminates in a ruddy great multiway connector that's on top of the gearbox, and not accessible with it in-situ, so it's an engine and gearbox out job.
That was probably very easy to manufacture too. At least the Omega's looms are out of harm's way and the connectors are accessible, on the whole.
Kevin