I am not sure I understand the question. Longitude values always range from -180 to 180, regardless of the datum (e.g. NAD 27). The datum is only used when converting between Latitude/Longitude coordinates and UTM coordinates.
Simple yet powerful utility to convert between a plethora of metric units.
Free latitude and longitude coordinates conversion tool.
Convert coordinates from one coordinate system to another.
I am not sure I understand the question. Longitude values always range from -180 to 180, regardless of the datum (e.g. NAD 27). The datum is only used when converting between Latitude/Longitude coordinates and UTM coordinates.