Aside from guesswork based upon reading through Emerald City and Sixth World Companion, I must have missed any direct translation of the older Zone Ratings to the new Lone Star security ratings. Can anyone pop those up here? Thanks!
You didn't miss anything! The CRB doesn't talk about Security Zones in a corporate-specific way. It was boneheaded to change them for flavor in Emerald City.
It's bad design to rename game mechanics for in-universe reasons. Like if Ares weapons started calling their firing modes Justice, Double Tap, Stay Down, and Bullet Freedom and appeared in the Gear Section as J/DT/SD/BF. What a mess.