Valentyn Moroz, one of the five dissidents who arrived in the United States Friday in exchange for two Soviet spies, reportedly plans to accept a standing University offer to assume a post at Harvard's Ukrainian Studies Institute.

"As far as I know, the only thing standing in his way would be a medical problem that prevents him from coming--we received a definite impression that he would like to accept the offer," Stephan Chemych, head of the Ukrainian Studies Fund (USF) that sponsored Harvard's invitation, said yesterday.

Chemych met with Moroz, a leading Ukrainian nationalist and historian, on Saturday. The 43-year-old author and teacher has requested a full medical examination, denied to him while imprisoned by Soviet authorities, before making any firm decision on the offer, Chemych added.

Moroz could not be reached for comment yesterday.

Though President Bok first invited Moroz and his family to spend a year at Harvard nearly five years ago, Moroz did not officially receive the invitation until yesterday, two days after his release.

Moroz told a representative from the Institute he was "very highly honored" to be invited by "the oldest and most prestigious university in America" for the 1979-80 academic year.

Ihor Sevcenko, professor of Byzantine History and Literature and associate director of the Institute, said Moroz would probably make his decision within "two to three weeks," after visiting Cambridge for discussions with University and Institute officials.

Although he said "we all very much hope he will be coming," Sevcenko would not confirm that Moroz plans to accept the offer. "It's much better to be cautious," he said.

Sevcenko said Moroz's position with the Institute, if he were able to come, has not yet been determined, but would likely take the form of senior research fellow. He described as "inexact" a Boston Globe report that Moroz has been offered a teaching post.

In 1974, while serving a 14-year sentence for "anti-Soviet propaganda and agitation" at Vladimir Prison near Moscow, Moroz went on a 20-week hunger strike to protest his confinement and poor living conditions at the prison.

During Moroz's hunger strike, at the urging of members of the Institute, Bok sent a letter inviting Moroz and his family to spend the 1975-76 academic year at Harvard. The offer has been periodically repeated since then, most recently in April 1977.

Moroz said this weekend that Soviet authorities had not permitted him to receive the letters, but his wife had informed him of the offer.

Moroz has been in Soviet prisons almost continually since 1965. After completing a four year term for alleged anti-Soviet activities, he was arrested again in June 1970 after nine months of freedom for writing a series of essays protesting Soviet domination of the Ukraine. His current sentence, five years imprisonment and five years exile, would have extended through 1984.

Along with fellow dissidents Aleksandr Ginzburg, Mark Dymshits, George P. Vins and Edward S. Kuznetsov, Moroz was exchanged on Friday for Valdik A. Enger and Rudolf P. Chernyayev, both United Nations employees convicted last year of spying for the Soviet Union and sentenced to 50 years.

Darkness at Noon