Scot Reader's Master List, accurate as of May 2009 I believe, can be found
here.
Meanwhile, PSA's T-206 Master Set Composition can be found
here.
PSA's list is missing numerous variations, and also has numerous cards that can't exist. For example, most people familiar with T-206s know that the O'hara and Demmitt St. Louis variations are rare because they were only printed with Polar Bear backs. Yet, PSA's Master Set composition lists 3 alternative, impossible backs for Demmitt and 1 impossible back for O'hara.
Not only is PSA's T-206 Master set impossible to complete, but if it were, it still would not even be close to a completion of the front/back combinations that are possible. So why is it even listed? Or why hasn't it ever been properly updated after all this time?
SIDE NOTE: Apparently Levi is the only guy on earth interested in making a go at it!