The route under the plenum & in front of the engine mount isn't great though - I would really prefer to run it behind the engine mount (bottom of picture) but its not quite long enough:
Its really hard to see from other builds the best way to do this; its just not feeling quite right at the moment - left or right of the chassis tube, infront or around the engine mount...
The current cable is 36" long (inner) and 32" outer. A 37" cable would be perfect - if I can work out where to get one.
Confirmed this routing is correct - just needs some cable ties to hold it in place.
There is also an option to notch the bell housing to allow the locking nuts to sit either side, I might do that in due course - alternatively - a cut through a nut would allow it to slip on the threaded end to the same effect.