To answer all the questions:
1. This is a correct color. My DuPont chart says 601 is Neptune Green on top, Shoreline Beige on bottom.
2. There is a discrepancy between my original DuPont charts from November 1954 and this GM specification chart
http://chevy.oldcarmanualproject.com/chevyresto/55024.htm , as the latter does not list this combination, while the OEM paint supplier (DuPont) does. My PPG chart agrees with my DuPont chart.
3.
http://chevy.oldcarmanualproject.com/chevyresto/55027.htm and the above-mentioned chart list all the interior color combinations. The metal on the interior is NOT painted to match the lower body color - it's painted to match the interior.
4. A 2 tone with the trunk and quarters painted the roof color is normally designated with an "S" suffix. "SPEC" is usually for a non-standard color - like the Army ordering 500 cars painted in Olive Drab. 601 is a standard code, so it should be "S", not "SPEC". Once again - a discrepancy.