You don't want to just cover them up, the flap opens under vacuum of a running engine to allow some airflow. A solid choke slide mod would be a flood-o-matic conversion.
Looks like on the three of them, you are missing the pin,. spring and choke flap. As you have one complete choke slide, you have a pattern to just make new flaps, pins and find suitable springs with proper tensile strength . If you are less ambitious, it should be easy enough to find those parts as the carbs are quite common. Maybe even a cheap rack for parts in general.
each of the choke slides are an assembly - Kawi part # 16126-1024.