M.A.C. PLAN SEEKS TORESTRUCTURE CITY FINANCIALLY
Munic Assistance Corp on Sept 2 offers to NYS Gov Carey and legis leaders stringent plan to restructure NYC financially, provide for possibility of munic default and virtually erase budget powers of Mayor Beame; plan includes $2.3-billion financing proposal to meet city's cash needs through mid-Dec and recommendations for eventual elimination of $3.3-billion deficit accumulated in operating budget; offers legis to spell out steps city could take in default to postpone debt payments while maintaining services; provides for creation of 5-member Emergency Control Bd that would in essence assume functions of Budget Bur and Controller; basic points apparently represent Carey's thinking; some specifics discussed; Estimate Bd, City Council leaders and Beame conf at Gracie Mansion; apparently concerned over some points; Beame and Deputy Mayor James A Cavanagh illus (L)