I can't answer your question unfortunately, but 2 turns isn't a hard and fast rule.
When you adjust idle mixture, your goal is to obtain the highest idle speed and correspondingly the highest vacuum reading. That may be 1-1/2 turns out, 2 turns out, 2-1/2 or anywhere in between.The 2 turns thing is a ballpark to get the engine to start after overhauling the carb.
