Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Those concave Cibie's are spot on Dave . I would definitely keep it despite being non-standard... I had one on the second 400/4 I had and far superior to the standard Stanley item. Did it have Fiamm Horns /K&N pod filters and Mars Chocky (Marzocchi ) rear shocks/Piper exhaust... all very common back in the day and all fitted to mine. For the life of me I can't remember the reg of that bike it was KJV P
Cibie did do 2 versions of the Z beam, the concave one was the 6.25" ? one for the 400 with the 7" being convex for the 500/550/750 etc. Oddly they are not marked on the glass to show they are the Z beam, I still have my 7" Z beam headlight and fully intend to refit it on the 500 when (or IF) the bike gets back on the road.I used the Z beam headlight as my testing bed for testing LED H4 replacement bulbs, you can see the results in the thread https://www.sohc.co.uk/index.php/topic,25595.msg234547.html#msg234547