The phase II route does exist, it has just OOS?? or landbanked?? since the 1970s. Runs from Stoughton through North Easton to Taunton. The consent decree between the state of Massachusetts and the Army Corp of Engineers, which is ridiculous, makes the former main line uneconomical to restore.
If you look carefully at google satellite view, you can see the abandoned ROW running through the Hockamock swamp.