In the news business, an exclusive story is a great coup for a reporter and his newspaper unless, of course, it remains exclusive.

Such has long been the plight of Tom Squitieri, formerly the one-man bureau for the Lowell (Mass.) Sun and now Washington correspondent for the Boston Herald.

Squitieri wrote a story on Dec. 14, 1986, that said about $5 million from Iran arms sales was funneled to conservative political action groups for helping pro-Reagan candidates in last year's campaign. The group mentioned in the story was the National Endowment for the Preservation of Liberty, run by Carl (Spitz) Channell.

The story hit the news wires and the Sunday television shows. R.W. Apple Jr. wrote a follow-up story in The New York Times the next day, crediting the Lowell Sun and also widely expanding the news of his scoop. But The Times and other news organizations said they could not confirm the story.

There it rested until last Tuesday when the congressional report on the Iran-contra investigation came out. The report says the committees "have uncovered no evidence to substantiate the allegation that NEPL or any other of Channell's political action groups received any proceeds derived from sales of arms to Iran."

The committees said they had accounted for virtually all of the funds received by Channell's organizations and all expenditures from the "Enterprise," the private operation set up to run the Iran-contra exercise for Reagan's administration.

At the Lowell Sun, Assistant General Manager Kendall Wallace, who was managing editor when Squitieri wrote the story, said his staff planned to do a story after talking to Squitieri. "It was a hot enough issue, and we owe the reader any information we get on it," he said. He said that Squitieri had other major international scoops that had been verified and until he knew differently, the paper intended to stand by the story.

Squitieri said that some members of Congress were disappointed that the investigating committees did not probe more deeply into some areas, including possible meddling in the 1986 campaign.

"I'm confident of my story, and I'm confident my story is as accurate now as I thought it was in the past," Squitieri said.

Under the category of rain that pours, Squitieri is also being challenged in his bid for the presidency next month of the National Press Club. An energetic young reporter with many friends in the media, Squitieri is vice president of the club, a job that in recent years has been a direct route to the presidency.

However, a mini-revolution has started, with Lee Roderick, Washington bureau chief for Scripps League Newspapers, also in the running for the top job.

Roderick, a former chairman of the club's board of governors, said his challenge of the recent club tradition had nothing to do with questions about Squitieri's story but with his view that the club needed someone with more managerial experience at this time.

"In looking ahead I felt my experience was more in line with what the club needs next year," Roderick said.

The Boston Globe, where there already have been two top editorial people since former editor Thomas Winship retired in 1985, may be considering still another change at the top, according to Globe sources.

One scenario has John S. Driscoll, who is now executive editor, moving up the corporate ladder to another title, perhaps editor. The newsroom would then become the turf of Driscoll's assistant executive editor, Benjamin Taylor, a former White House correspondent considered a possible heir to the top job in the Globe publishing empire.

The younger Taylor, who is a distant cousin of Globe Publisher William O. Taylor, would become executive editor, according to this scenario.

Asked about the proposed changes, Benjamin Taylor said he had no comment except to say that a story last week in the Boston Herald that speculated about possible shifts in the Globe's management team was "full of errors." He declined to elaborate.