BOSTON — A major memorial honoring Martin Luther King Jr. and Coretta Scott King is moving forward in Boston, where they met and studied in the 1950s. King Boston, the privately funded organization coordinating the estimated $9.5 million project, said this week that fabrication of a roughly 22-foot-high bronze sculpture depicting four arms embracing is expected to begin in March after years of planning. When unveiled late next year, “The Embrace” will be one of the country’s largest new memorials dedicated to racial equity, the organization says.