You can get by without a choke, if you solder a nipple to the steel diaphragm cover. That is the carb's pressure regulating part. Put a tube on it, and blow on it whilst starting. Now the carb will pump fuel into the engine like an injection system.
During the warm-up, blow as required.
I had a Quadra equipped that way, and it worked very well with the cylinder in 6 o-clock position (carb horizontal)