What is this?

What year is the car? The fitting is a temp sensor, for either emisions, or lean burn. Don't worry about it. Just leave it as a plug in the hole. The carb is not correct for any Mopar. It is either a aftermarket Holley 350 cfm, or 500 cfm (need the numbers on the air horn). Or it could be from a Ford (not likely). You do need to hook up the PCV system, and the distributer advance to the ported vacuum port on the carb. Also, check for any vac leaks. Start with that.
The large hose from the manifold vacuum tree, that goes toward the carb. What is it connected to? Also the small hose from the vac tree, looks to be going to the carb, It should not.