President-elect Ronald Reagan's team has put the finishing touches on a White House staff plan that will filter most advice through his top two deputies and apparently give more day-to-day supervisory authority to James A. Baker III, a newcomer to the Reagan circle, than to veteran Reagan lieutenant Edwin Meese III.

The authoritive source who made the description of the White House structure available to The Washington Post also provided the first solid evidence that Reagan plans to give Vice President-elect George Bush as much access and influence as Vice President Mondale has enjoyed in the Carter White House. According to the source, Bush will "attend all the White House meetings Mondale has attended" and will have a regularly scheduled weekly lunch with the president, as Mondale had had with Carter. Bush's top assistant, retired admiral Frank Murphy, will attend White House senior staff meetings, the source said.

Meese, the counselor to the president, and Baker, the chief of staff, occupy parallel positions atop the staff pyramid. But the source said only three of the 14 members of the prospective staff would report to the president through Meese and 11 would report through Baker.

As previously disclosed, Meese, the San Diego lawyer who served as Reagan's top assistant in his second term as governor of California and prevailed over John P. Sears in a struggle for control of the presidential campaign, will run the policy side of the White House. Baker -- who was President Ford's campaign manager in 1976 and served in the same role for Bush in 1980 -- will manage the political and administrative operations for Reagan, a man he first began helping only last summer.

Emphasizing the growing influence of the Houston attorney is the disclosure that -- at least according to this blueprint -- all papers and personal appointments for the new president, including those generated by Meese's side of the White House, will be coordinated and filtered through Baker's office.

That is only one of several features of the Reagan White House design that officials in the transition team concede will have to be tested in operation before it can be regarded as final.

In a major departure from past practices, Reagan's principal policy advisers on domestic and national security matters, Martin Anderson and Richard V. Allen, are shown as reporting through Messe, rather than having the direct access to the president their counterparts in previous administrations enjoyed.

Also to be tested is the design that puts Baker between the president-elect and two of his veteran and intimate political advisers, Michael K. Deaver and Lyn Nofziger. The organization chart shows Deaver as deputy chief of staff, responsible to Baker for four administrative functions, and Nofziger as the assistant to the president for political affairs, one of eight or nine staff positions reporting directly to Baker.

According to the source, other senior aides who will be under Baker's wing include the assistant for legislative affairs, Max Friedersdorf; for public liaison, Elizabeth Hanford Dole; the press secretary, James S. Brady, and the yet-to-be-named legal counsel, communications, personnel, intergovernmental affairs and speech writing chiefs.

Operting under Deaver's direction will be the directors of the First Lady's office, Peter McCoy; scheduling, Joseph Canzeri; military support services, Edward V. Hickey, and the yet-to-be-announced director of advance operations.

A number of the vacant positions on the organization chart have been filled, the source said, but have not yet been made public. One position that he did disclose was the choice of Richard S. Beal, a 34-year-old professor of international relations at Brigham Young University, as director of planning and evaluation under Meese. Beal is an associate of Richard Wirthlin, Reagan's campaign pollster and strategist, but the source said the function of the new office would not include survey research for the White House.

Rather, he said, Beal will head a small staff monitoring long-term projects of particular importance to the president in an effort to see they are well-coordinated across agency and departmental lines.