In his modest office on Queen City Drive, the reminders of a grander time are all about him - the pictures of Gerald Ford and Mamie Eisenhower, the official White House pens used to sign bills into law, the certificates attesting to his service in the U.S. Senate and House of Representatives.

Yes, the middle-aged man in the charoal grey, pin-stripped suit admits, he misses his old job. "It's exciting to be in Washington, particularly in a place like the Senate," J. Gleen Beall Jr. said in an interview lst week. "You miss the constant activity, the involvement in public affairs."

But Beall is no longer in the Senate. He's back home in Allegany County selling insurance. He's back home reflecting, sorting out his life, and giving out clear signals that he does not think his political career is over.

"I want to keep politically active. I'm not ready to retire when I'm not quite 50 years old," he declared. "I'm keeping an open mind on my options."

The biggest thing Beall is keeping his mind open about is the 1978 gubernatorial race in Maryland. Although soundly beaten in his bid for re-election last November by Sen. Paul Sarbanes, Beall is the best known of the half-dozen or so Republicans frequently mentioned as candidates for the governor's job.

Two of the other most prominently mentioned contenders, former Republican Reps. Gilbert Gude and Lawrence J. Hogan, have both recently taken other jobs that appear to take them out of contention, Gude, of Montgomery County, has been named director of the Library of Congress' congressional research service. Hogan, from Prince George's County, has become executive secretary of the Associated Builders and Contractors, a trade association.

Beall isn't making any overt moves toward the nomination, and some GOP regulars are very cool to talk of his candidacy. "Everyone I talk to says he couldn't win," said one party leader. "After the last election, we're looking at a 15 point loss (Beall's margin of defeat by Sarbanes) from the beginning."

But in a state where Republican Party fortunes are at low ebb. Beall speculates that 1978 might provide the right ingredients for a GOP upset - one that could propel him or his brother George, a former U.S. attorney who is also mentioned as a Republican contender - into the governor's mansion.

"Democrats have to be fragamented for a Republican to win in Maryland." he said, musing over the long list of prominent Democrats considered as potential candidates. "The kind of situation you have developing offers the real potential for fragmentation."

Beall, however, had some tough words for the Republican Party in a two-hour interview in his office at the Beall, Grner, Screen and Geare Insurance Co. here. During his campaign last fall, he said, he found the GOP in Maryland a party without organization or workers in many counties.

"The Republican Party has to reach out," he said. "It has to have more blacks, more labor support and a bigger financial base. We have to go out and bring people into the party, rather than spending our time fighting with one another over ideology."

Big party politics seems very distant from Beall's office in this small mountain city in western Maryland.

Beall, who grew up in nearby Frostburg, spends three days a week here. He became president of the firm, the largest in western Maryland, last month. He retained interest in the company, which he formed in 1964, through his years in Congress, and served as chairman of its board of directors, a job that paid him $20,000 to $25,000 a year.

The firm became an issue in his re-election campaign when it was learned it did more than $1 million dollars in business with public agencies in western Maryland, leading to charges of political influence pedling . Beall consistently denied that he had anything to do with contracts with public agencies. If he had used his political pull, he said at one point, "there would be a lot more business."

"The reason that I maintained my interest was so I could have something to come back to," he said last week. "This job gives me a great deal of flecibility. I prefer it to being a lobbyist in Washington."

But like most defeated senators, Beall hasn't severed his ties with Washington. He and his wife still maintain their home in suburban Bethesda, and will continue to, at least until their daughter, Virginia, a junior at Holton-Arms, finishes high school.

In his way, Beall can continue to keep close ties to Washington have the freedom to move about, and be free to campaign for office if the chance arises. "I don't want to step totally out of public life," he insisted. "I have an interest in what goes on."

But as for the governorship, Beall added, "It's purely in the mentioning stage right now. A lot of people have asked me about it. I tell them I'm not closing the door on anything.

"As for now, my goal is to be the successful president of an insurance company."