You can turn the carb in any direction that suits you. I recommend that it is firmly seated and sealed, and that the throttle is positioned so that its movement and control of that movement is not impeded.
One of the first mods most people do is a carb flip. They turn the carb so that the throttle arm is on the right side of the truck vice the left side (this is for those with a rotary carb...some with slide carbs do this also).