President Carter's choice to head the General Services Administration said yesterday that his first concern would be to work closely with the Justice Department and GSA's inspector general to complete ongoing investigations of GSA corruption.

Rear Adm. Rowland G. Freeman III, a defense procurement expert, set this priority as the White House announced that President Carter, as reported, would nominate him to be administrator of the scandal-plagued agency.

Freeman's nomination much be confirmed by the Senate before he canreplace Jay Solomon, whose resignation as GSA administrator is effective March 31.

"As this investigation is conducted, I want to rebuild GSA into an efficient and effective support agency," Freeman asserted. "I will build on previous studies of GSA problems -- and call toghther experts from the public and private sectors and the academic community to help.

"While I acknowledge that GSA has serious problems, I am convinced in my own mind that none is so severe that it cannot be solved. I will establish firm goals and objectives for GSA; goals and objectives which GSA employes can understand and meet through hard work and imagination.... I am going to be proud of GSA."

"We will examine any possibility of wrongdoing," Freeman said in a prepared statement. "I want to be absolutely sure -- and assure the Congress and the president -- that any wrongdoing in GSA is ended."

Freeman who plans to retire from the Navy if he is confirmed as GSA administrator, has given a number of speeches and written articles about the procurement business. They deal with the intricacies of managing major purchases.

"... There is very little which is new or magic that can be called upon when managing uncertainty in the acquisition of major projects," Freeman said in a speech delivered last month to the University of Southern California's Graduate School of Business Administration.

"The manager's job is one of looking for solutions to unsolvable problems. Dealing with uncertainties is the prime reason a manager can justify his salary."

He said "cost growth" or cost overruns that increase the price of a project may not, in fact, represent a waste of money, since the original cost may have been estimated improperly.

"Thke, for example, experience on a recent major aircraft modification, where the successful bidder was about 25 percent lower than the next nearest bidder," Freeman said. "It was the engineering opinion of government engineers that the contractor did not understand the required development. Yet, the contract was let. The program subsequently was plagued with cost growth, disruption, delay, and a less-than-acceptable product."

From 1966 to 1968, Freeman was the Navy's project manager for the F-111B aircraft, a project that produced huge cost overruns and experienced technical problems. The Navy decided not to go ahead with the project, while the Air Force did.

For the past two years, Freeman, 57, has been commandant of the Defense Systems Management College, which trains procurement experts at Fort Belvoir, Va., to buy goods and services in the most efficient manner.

An official of the school, who asked not to be named, described Freeman yesterday as a "good influence" on the school.

"He's a stimulating individual who is an effective manager," he said. "He works hard and pushes people."

In another development involving GSA, Solomon announced that he had split the agency's five-state regional office that includes Washington. The National Dapital Region will cover the Washington area, while Region 3 will include the remaining areas and will be runfrom Philadelphia, he said.