On a somewhat related note (researching another CIA person), how high in the chain would a GS-15 be?
A GS-15 is the highest step one can reach in the Civil Service before being promoted to the Senior Executive Service. A GS-15 is roughly the equivalent of an O-6 (Colonel in the Army, Air Force and Marine Corps, or a Captain in the Navy or Coast Guard). At least that's about how it was when I retired in 1997.