If by NC&SL you mean the Nashville, Chattanooga, and St. Louis that railroad was bought by the Louisville & Nashville and is a CSX predecessor.
NS did not forget the TAG. They had 18 schemes to choose from, and the TAG was initially in the running, but ultimately was not included because of the almost non-existence of any of that trackage left in the NS and its relatively minor contribution to the company's history.
These things were carefully thought out, and people well versed in the roles the predecessor roads played in making NS what it is today were involved throughout every step of the way. It was not simply a matter of sitting down and mapping every railroad that preceded the present Norfolk Southern.
Mike Derrick
[
www.shortlinesusa.com]