Carb linkage and adjustment questions

Sooooo....help me understand this. How far open should the butterfly on the carb be? If I were to just attach it with the linkage at the existing angle, it would be at least 1/4 of the way open.
Has the linkage been altered or adjusted to fit the bastard carb that is on there now? What do I need to do to install the Carter BBS and set the linkage and throttle properly?