The House Appropriations Committee yesterday gave the Bush administration all the additional funds it sought for the Internal Revenue Service next year as panel members also channeled millions of dollars to projects in their home districts and those of other key legislators.

A $20.7 billion fiscal 1991 spending bill for the Treasury Department, Postal Service and general government would increase IRS funding by more than $600 million, primarily to pay for a modernization of the agency's computer system. The measure also included projects requested by such House powers as Rules Committee Chairman Joe Moakley (D-Mass.), Majority Whip William H. Gray III (D-Pa.) and Rep. Silvio O. Conte (R-Mass.), the ranking Republican on the committee.

The action came a day after the full committee accepted a number of pork-barrel highway and bridge amendments to the 1991 transportation bill from members of the transportation subcommittee, who used the occasion to add more projects to a bill that they had drafted earlier at a closed session.

The display prompted Rep. William Lehman (D-Fla.), who chairs the transportation subcommittee, to gently chide panel members for coming in late with additional proposals.

Lehman's own project, a $2 million grant to Mt. Sinai Medical Center in Miami, was contained in the Treasury spending bill approved by the full committee yesterday. The Treasury bill, which includes the budget of the General Services Administration, has become a bonanza for members and lobbyists.

The Miami grant was part of a lengthy list included under the category of "General Services Administration Real Property Activities." Mixed in with funds for new courthouses and government buildings were grants for a National Center for Complex Systems at Brandeis University near Boston ($5 million); the Marine Biomedical Institute for Advanced Studies ($6 million) in Woods Hole, Mass., and the University of Maryland at College Park's research on superconductivity materials ($1.5 million).

Conte was among those backing the Brandeis grant, while Moakley, who is not a member of Appropriations, was instrumental in getting the $51.3 million for a new federal building and courthouse in Boston, and Gray was credited with garnering a $778,000 grant for a group called Parents Against Drugs in his home town of Philadelphia.

Meanwhile, at a closed-door session yesterday, the military construction appropriations subcommittee approved a 1991 budget of $8.3 billion that reflects changing priorities. The figure was $800 million less than the president requested and $200 million lower than current fiscal year spending.

Doubts about the future of the MX rail garrison intercontinental ballistic missile program prompted the subcommittee to defer $254 million sought for three planned MX bases, including one at Fairchild Air Force Base in the eastern Washington congressional district of House Speaker Thomas S. Foley (D-Wash.).