Very well put and helpful, Jon. Two comments I'd add:
1. I prefer automatic chokes and in my opinion Carter YF auto chokes work very well. Actually I think they're better at their job than I am.
2. Carter YF identification simply by the number stamped on the float bowl can lead a person down the wrong path. If the carburetor has no tag, it probably means it has been commercially rebuilt. And this may mean your air horn and float bowl are no longer anywhere close to being matched. I see these being sold on eBay
constantly. Take a look at this one (which has been listed on eBay for about 2 years now):
https://tinyurl.com/ups28yo The only part of that carburetor that I believe is a 3211s is the float bowl. Everything else is pure alphabet soup. There's another one listed as a 3211s which claims to have been taken off a running engine. The air horn for it isn't a 3211s either (if you look you can see the castings are different colors and if you look at the 3 NOS models I have listed, you'll see another interesting difference) and guess what...no tag. At least it is closer than the first one...but I wouldn't buy it.
