By Zach Koons The high-flying Grizzlies star called the slam the best of his career to this point. Grizzlies star Ja Morant never fails to amaze with his high-flying play and jaw-dropping dunks. But on Saturday night, the 23-year-old uncorked a slam that even he said was the best of his career. With just over four minutes left in the third quarter of a road game against the Pacers, Morant easily carved his way past a pair of defenders, clearing himself a runway to the rim. At the last moment, Indiana center Jalen Smith slid over to help, but instead offered himself up to be posterized. Morant …