The engine lit right off, and sounds good when the RPM is high enough to handle the cold A/F mixture and temp. If you have an automatic choke you should be able to adjust the high speed idle screw, usually with the choke linkage on the passenger side of the car. As the auto choke opens the high speed cam will drop off when the throttle is opened, allowing the idle speed to drop to the next lower choke high speed cam position, or to the mormal idle once the choke is open enough. That would help keep you from having to manually hold the idle speed higher than normal when the engine is cold and the choke is on.
If you have a manual choke you ought to still have a fast idle adjusting screw near the choke linkage.
If you are not familiar with setting the high idle speed using the choke linkage I show how to do that on an Autolite 2100 2 barrel carburetor. Most carburetors are adjusted in a similar manner, so this ought to give you a nice head start with your carburetor.