Three finalists have been chosen by the General Services Administration in a design competition to develop a plan for the area around the Old Post Office. The winner will be given a contract to design a master plan for the entire Federal Triangle area, according to General Services Administrator Jay Solomon.

In January the Fine Arts Commission held up approval of the $18-million plan to remodel the Old Post Office until they were assured that GSA would complete the site plan. For 187 years people have argued over the area's design.

The biggest problem is to heal what Fine Arts Chairman Carter Brown called the "truncated stumps, the bleeding amputated limbs" where the Classic Revival Federal Triangled Buildings (in what was to be a great circle) meet the Richardson Romanesque Old Post Office.

The designers could recommend an addition to the Internal Revenue Service building. Solomon has asked that they come up with a way of linking the downtown shopping are with the governmental offices and the museums' mall. Landscaping and sculpture are among Solomon's prime requirements for the plan.

Finalists will consider the site bounded by the New Post Office Building, Constitution and Pennsylvania Avenues and 10th Street. The entire Triangle, to be designed by the winner, goes from the Gran Plaza at 14th Street to 6th Street between Pennsylvania and Constitution Avenues.

The three finalists are well-known here. Harry Weese and Associates of Chicago designed the Metro Stations and Arena Stage. Jerome W. Lindsey and Associates of Washington are architects of the Gage-Eckington and Perry Simmons Elementary Schools here. They are in a joint venture with Sert Jackson and Associates Inc., and Lozano, White and Associates, both of Cambridge, Mass., and SWA Group of Boston. Sasaki Associates Inc. of Watertown, Mass. (who worked on the Federal Home Loan Bank Building here) are in a joint venture with Gindele and Johnson of Poughkeepsie, N.Y., and Shepley, Bulfinch, Richardson and Abbot of Boston.

Each will receive $40,000 for their design, to begin June 22 and to be finished by August 21. No amount has yet been set for the winner's contract for the whole Triangle, though GSA project director Jack Loxley said GSA will ask Congress for planning money in October.