Chances of the city government winning congressional approval to buy the four-acre Shapiro tract in Adams-Morgan for a park improved this wek on Capitol Hill.

Rep. William H. Natcher (D-Ky.), chairman of the House District Appropriations Subcommittee, said at hearings that conditions that led him to block the purchase on two occasions have changed.

"The committee is going to give this matter every consideration," Natcher told a delegation of citizens led by Stephen Klein of the Adams-Morgan Advisory Neighborhood Commission and David A. Clarke, a City Council member.

The delegation asked the subcommittee to approve the city's expenditure of about $2 million to buy the land. It is seeking $500,000 in the pending capital improvements budget, to be added to $1 million to be transferred from other city projects and $500,000 granted by the federal government.

The city plans to construct athletic facilities in the new park.

Natcher said it did not bother him that a development firm, the Holladay Corporation, took a 90-day option on the tract in March as the possible site for a 100-unit townhouse development.

The city, Natcher said, could acquire the land by condemnation through the courts if Holladay decided to exercise it option and buy the land from its owners, Maurice and J.B. Shapiro.

The tract, once the site of an apartment house, is between Calvert Street, Adams Mill Road and Rock Creek Park. It is the last large piece of vacant land in Adams-Morgan, a neighborhood whose center is 18th Street and Columbia Road NW.

Natcher said he had opposed the purchase in the past because there was too great a disparity between the price the city planned to pay for the land and its assessed valuation for tax purposes.

Originally, Natcher said the proposed price was $4 million, while the assessed valuation was $351,000. The proposed price has been lowered to $2 million and the assessment raised to $1.1 million - figures he said seem realistic.

At least three witnesses who appeared individually at the subcommittee hearing on Monday testified against the Shapiro tract pruchass. One of them, Martin F. McMahon, said the proposed park is "a luxury item the city (we taxpayers) simply cannot afford."