Bewy said

There might be a problem with what has been done in post #10. There is usually a manifold vacuum port that connects to these types of choke units. What it does: if the throttle is opened suddenly with a partially closed choke, the choke blade is opened via the linkages to prevent engine stalling.
There is a boss on the carb behind the choke unit that is drilled for man vac. On carbs that did not have a choke originally, this boss would not be drilled or might be plugged.

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