The model number for your carburetor should be stamped upon a rectangular boss on top of the carb body casting.
Your bowl vent will be very, very much smaller, with its location dependent upon the model, but completely separate from the venturi vent.
Vents to the venturi void supply air to the main nozzle upon accelleration and highspeed cruising;
M-36 models for 1949 had a much smaller small side-vent upon a raised boss,
but I haven't a proper reference pic for later '49 M-45s handy to coagulate my memory if they had returned to the large orifice so soon or not.
Got macro pics?
Dumpster Diver's Motto: Seek,... and Ye Shall Find!