What 2bbl carb is this?

[KULTULZ]

Also, I noticed at least one of the openings in the choke housing (maybe both) are drawing vacuum when the car is running. Should those be closed off? There are two of them and they should be visible in the photo.

That is the vacuum signal drawing heated air from the choke stove. The RS is from the brass fitting inlet we were discussing. The LS is the source of the manifold vacuum signal. The drawn heated air operates the thermostat spring.

If a thermostatic choke, both should be open. If converting to an electric choke kit, the inlet line with the brass fitting should be either blocked of (plumbing fitting brass block-off cap) or as mentioned the HOLLEY CAP that will allow outside air to cool the electric thermostat (photos provided in above post).

Choke design varied over the years, and yours is unique. The correct year WSM (1961 MERC) will give you all the info you need.