Chevron formally asked the Federal Trade Commission for permission to fold Gulf Corp.'s domestic oil and natural gas operations into its own . . . San Francisco-based PacTel InfoSystems has signed a lease for its first retail microcomputer store. The store, located in San Mateo, Calif., will offer microcomputers, telephone systems, software and accessories . . . Martin Marietta's board of directors approved a 3-for-2 common stock split and increased the dividend rate by 11.9%. Both actions are subject to shareholder approval and will be payable June 28 to shareholders of record June 3 . . . Beatrice Cos. of Chicago said it has completed the previously announced sale of its chemical operations to London-based Imperial Chemical Industries for $750 million in cash . . . Agriculture Secretary John R. Block, who vowed earlier that the deadline to sign up for 1985 crop programs would not be extended, announced that the date has been extended a month to April 1.