SPRINGFIELD — Two years after stepping down as head of the state’s medical cannabis pilot program, health-care attorney Robert M. Morgan hopes to reduce health-care costs, push for gun safety laws and look for ways to lower property taxes when he takes office Tuesday.Morgan, an attorney at Much Shelist P.C., was elected to represent the state’s 58th District on the North Shore. The Deerfield Democrat starts his role as a state representative on Jan. 8, filling the seat currently held by Rep. Scott R …