Complex sentence: McKay also worked in the academic arena as first a full-fledged Associate professor, at the Brigham Young University Law School from 1974 to 1976 and later became a lead Professor at Brigham Young University Law School from 1976 to 1977.
Split into simpler sentences: McKay also worked in the academic arena as an associate professor at the Brigham Young University Law School from 1974 to 1976. He later became a full professor at Brigham Young University Law School from 1976 to 1977.