Squidles,
Now I know why 'Squidlydot' sounded familiar-!
You just missed out on a 67-7026 on ebay, I was on the hunt for one too, and ended up swapping one locally. I also found out the early ones don't have an 'Adjuster Lug', as do the post '53 (thanks to Brian- I think), and also it interferes with the exhaust so needs adjusting but you may get lucky!
As a backup, I found a lever at a swap with no number, but I think it's early A65, that may do the job in an emergency.
It looks a lot like the A10 S/a ones (42-4347/42-7042&4) they fit~ but don't do the job.
Also you brought back memories 'bout the cases- I had to repair several chunks of chaincase,so have had to do a lot of improvising, so will never be very original.
Richard I think it's saltbox Alf in S-france?