After a nearly six-month delay, the administration is finally ready to name the members of a new presidential study commission on antitrust.

Sources said yesterday that at-large members of the panel, whose primary mandate is to study and make recommendations on ways to expedite complex antitrust cases, will include:

John Izard, a partner in the Atlanta firm of King & Spalding, Attorney General Grifin B. Bell's former firm.

Eleanor M. Fox, an antitrust lawyer who currently teaches at New York University Law School and is associated with the New York firm of Simpson, Thatcher & Bartlett.

Gordon B. Spivack, an antitrust lawyer with the New York firm of Lord, Day & Lord, who also is a visiting lecturer at Yale University. Spivack worked for the antitrust division of the Justice Department from 1955 to 1967 in various posts from trial attorney to Director of Operations before leaving to join Yale's faculty.

Maxwell M. Blecher, a well-known plaintiff's antitrust lawyer with the Los Angeles firm of Blecher, Collins & Hoecker.

Craig Spangenberg, of the Cleveland law firm of Spangenberg, Shibley, Traci & Lancione. Spangenberg has been active in the Association of Trial Lawyers of America.

Lawrence A. Sullivan, professor of law at the University of California at Berkeley and author of an antitrust textbook.

Also to be named to the commission is United States District Judge C. Clyde Atkins for the Southern District of Florida, who has been on the bench since 1966.

John H. Shenefield, assistant attorney general in charge of the antitrust division, will be appointed chairman, sources said.Originally, Attorney General Griffin Bell had hoped to name Izard the panel's chairman but the selection was objected to by Senate Antitrust and monopoly Subcommittee Chairman Edward M. Kennedy (D-Mass). He had argued that the commission chairman should not be so closely identified with the defense bar and that a more neutral selection would be better.

Federal Trade Commission Chairman Michael Pertschuk and Civil Aeronautics Board Chairman Alfred Kahn also are slated for membership, as are five members each of the House and Senate, selected by them. The Senate members will be Kennedy, Howard M. Metzenbaum (D-Ohio), Robert B. Morgan (D-N.C.), Jacob K. Javits (R-N.Y.) and Strom Thurmond (R-S.C.)