John G. Tower, recently retired chairman of the Senate Armed Services Committee, is the likely candidate to succeed Arthur F. Burns as ambassador to West Germany when Burns retires this year, administration sources said yesterday.

The sources said Tower, a Texas Republican who did not seek reelection last year after 22 years in the Senate, has had "several serious discussions" with senior White House and State Department officials about taking the Bonn embassy and probably will get the post if he wants it. But they said both he and the White House have deferred a final decision because former Federal Reserve Board chairman Burns, 80, plans to remain on the job until after the Bonn economic summit in June.

Tower has been an influential force among Senate conservatives. His appointment to Bonn would be welcomed by the Republican right, which has expressed concern that a reshuffle of key foreign policy posts is an attempt by Secretary of State George P. Shultz to purge conservatives from positions of influence within the State Department.

However, the sources said, Shultz reportedly is enthusiastic about the prospect that Tower might go to Bonn because his expertise in military affairs would be an important asset in the country that is probably America's most important NATO ally. Similarly, the West Germans prefer the U.S. ambassador in Bonn to be a political appointee who has direct access to the White House rather than a career diplomat.

In regard to other aspects of the controversial State Department shake-up, the sources said Shultz wants to replace Richard T. McCormack as assistant secretary for economic affairs with John Michael Hennessy, a banker and economist who served under Shultz when he was Treasury secretary in the Nixon administration.

But, the sources continued, that move has run into snags because of conservative pressure to find another post for McCormack, a former aide to Sen. Jesse Helms (R-N.C.), the dean of Senate conservatives. McCormack reportedly does not want an overseas assignment, and the sources said one solution under consideration is to make him ambassador to the Organization of American States.

If McCormack goes to the OAS, he would replace J. William Middendorf II, another outside appointee with ties to Helms. Shultz wants Middendorf to become ambassador to the European Economic Community, headquartered in Brussels, and the sources said Middendorf is expected to accept the assignment change despite pressure from conservatives for him to be kept in Washington.

The sources also said that, while Shultz appears to be making some tactical concessions to defuse conservative complaints about an alleged purge, he is largely succeeding in his determination to staff a number of important embassies, particularly in Latin America, with ambassadors chosen from the career Foreign Service.

They said that John A. Ferch, a career diplomat who has headed the U.S. interests section in Cuba since 1982, will become ambassador to Honduras, succeeding John D. Negroponte, who is being reassigned to Washington. That resolves a fierce dispute caused by Shultz's original intention to send L. Craig Johnstone, a deputy assistant secretary for inter-American affairs, to Honduras.

That decision was reversed because Johnstone did not want the assignment for personal reasons and because conservatives charged that he did not have a sufficiently tough attitude toward the radical leftist government in neighboring Nicaragua. Johnstone, who wants to leave the Latin American area, now is slated to become ambassador to Algeria.

The sources said another major shift in Latin America will send Harry G. Barnes Jr., now ambassador in India, to Chile. Barnes is regarded as one of the "stars" of the career Foreign Service; and his reassignment to the smaller embassy in Santiago is regarded as a sign of mounting concern within the State Department that rising discontent against Chile's military government could make that country a serious crisis area.

Barnes will replace James A. Theberge, a conservative political apppointee who has opposed moves to reassess the U.S. policy of close association with the Chilean military regime. The fact that Theberge is not slated to get another assignment has helped to fuel conservative suspicions of a purge.

The sources said that other planned ambassadorial changes involving career officers in Latin America will send Lowell C. Kilday, a deputy assistant secretary, to the Dominican Republic and Charles A. Gillespie, also a deputy assistant secretary, to Colombia.

Some sources had said earlier that Gillespie, who oversaw U.S. activities in Grenada following the U.S. invasion of that Caribbean island 15 months ago, would become ambassador to Bolivia. However, the sources added, that plan was changed after death threats from drug traffickers forced the withdrawal of Lewis A. Tambs from the Colombia embassy.

Tambs, a history professor with strong conservative convictions, will become ambassador to Costa Rica; conservatives, who had feared that he would be dropped from the administration as Theberge was, have hailed his new appointment as a victory. State Department officials insisted, however, that his assignment to Costa Rica was made not on ideological grounds but because of a feeling within the department that he had done a good job in helping to stem the cocaine traffic from Colombia to the United States.