Unless the OP can find another carb to use or to strip he in trouble as the cast throttle is broken. And for this older slide choke carb new parts are not available nor is the carb. No separate throttle plate used. See circled area.
[Linked Image from i.imgur.com]
Of course if someone can weld a new tab on the throttle then it might work.

Cast throttles are removed by backing off the idle speed adjustment screw until the throttle clears the retaining lug on the carburetor body which in this case is already removed.