Thanks guys. So as per the parts manual, my bike (1956) should have no pilot (up to 1955) light or grommet (up to 1955). I'll plan for a slot cut out as in the pic with the pilot light. I see no other hole for the wiring loom so I assume this comes in the same slot.
The attached is maybe what I should be aiming for? (without the homemade hole in the middle).
Cheers, Chris
I'm still puzzled as to why you need a slot and/or cut out? Only a few wires need to go into the headlight shell (switch and ammeter being outside of it) and these wires will easily fit through a small hole maybe 10mm diameter (with grommet fitted to protect the wires). This could be the hole you think should not be there
Note rightly or wrongly I DO have a pilot light on my 56, not the underslung type, but a separate small bulb fitted in the reflector.
Edit: I've re read the earlier posts and what you called a tubular grommet, is present on my 56, exactly the same as it is on the shell with the underslung pilot light, and as the pic posted by chotus52.
My guess (others to confirm/deny) is that all the "cow pat" nacelle models need to have the speedo cable passing through the headlight shell, whether they have the underslung pilot or not.
I'm not sure how the speedo cable is routed on the later nacelle models.
On models with NO nacelle eg those with "ears" on the shrouds, I would have thought there would also be no need to pass the speedo cable through the headlight shell. I guess this would also probably apply to models with rev counters?