Mark, that's a good question ! of which an answer appears not to be found anywhere i look in the website !
The lengths of the choke levers are addressed in #12 of the "Distinctions" thread. But, change in the length of which we could suggest a vin where the shorter lever was first seen, is not present.
I do remember when i put that list together, I realized we did not have/know a 'vin break' where the lever went from long to short. Seems i would have had discussion(s) with other members about such a significant detail, but i surely cannot recollect such a discussion, assuming i ever had one.......
Will be good to hear what fellow members report !
(Was surprised when i found brake line info in the carb section of "Prod.Models"....... ?!? I loaded that info. What was i thinking/drinking !?!)