ATLANTIC CITY, N.J. -- The troubles Gerry Cooney has known would fill The Ring boxing encyclopedia (1,000 pages). Injuries. Depression. Family troubles -- big troubles: a brother on drugs; a father dead of cancer; a mother in need of her strongest son. Cooney has found so little time to fight he takes up only one-quarter of a page in The Ring's big book.

Now, Cooney believes his troubles are over. To believe with him takes a leap of faith, given his history and a fate that surely awaits him. On Monday night, he faces undefeated Michael Spinks and, if he beats Spinks, eventually, inevitably, he will fight undefeated Mike Tyson. One or the other promises more trouble for Cooney. Cooney may be big enough to handle trouble -- 6 feet 6, 230 pounds -- but trouble always gets him. Could Cooney's boxing career end any way but in a sadness that has undeniably surrounded it?

Forget, for the time being, all that's gone before. A promoter's pathetic Great White Hope hype that saddled him before he fought Larry Holmes in 1982. The depression from that defeat that sent him into hiding. A torn rotator cuff, damage done before he fought Holmes, that hampered his money punch, his left hook -- who can be sure the arm won't go again?

Forget the worries his brother has caused him. Forget the look in his baleful brown eyes when he recalls the hurt he has known both in and out of the ring.

Gerry Cooney, at 30, looks great. Even with his perpetual unshaven look, the stubbly growth of at least five minutes. With a practiced tone, he said, "The past is yesterday. I'm looking forward to tomorrow."

Then he spoke more earnestly, leaning forward in his chair, pulling his little gray cap lower toward his big brow. "I think I'm the best heavyweight in the world right now. Everything's going very well. My brother's doing very well. My family's doing fine. I feel great."

Softly, gentlemanly, he said: "I want to win. For myself, first. And for all those people who stuck with me and understood.

"My brother was addicted to three major drugs, and I had to step away from boxing for a while. I've been criticized for it. But if I had it to do over, I would do it the same way because in life you can have many careers, but you only have one family.

"Drug abuse is a very difficult disease. When you see a family member you love and grew up with . . . That was a very serious thing that I put on my shoulders. But right now, he's recovering in a rehabilitation center and doing very well and one day he'll lead a very productive life again. If I would never fight again, as long as I accomplished that for my brother, hey, that's life, that's the way it's supposed to be."

He spars four rounds with Melvin Epps, who is quick and shifty, something like Michael Spinks. Then two rounds with Lorenzo Canady, nothing like Spinks. Cooney cuts off the ring with two large steps and lands a hook to Canady's jaw. Canady's mouthpiece flies across the ring. Gasps fill the ballroom of the Trump Plaza. Guys wearing "Gerry Cooney, 'It's About Time' " white T-shirts applaud. Against the ropes, Canady shakes his head, trying to clear it. Cooney, black shirt, black shorts, waits for him. He's, after all, "Gentleman Gerry." 'Greatest Transition'

"Time," someone yells. Dennis Rappaport, Cooney's manager in a Panama hat, gold jewelry and tomato-red sweater, senses the time is near when Cooney will affect a different look. "It's amazing," said the fast-talking Rappaport. "Before it's time to go out to fight, you see the greatest transition, not a guy looking to psych himself up or being loud. It's the look in his eyes. And then we know it's time to go."

Tape is unwound from Cooney's fists and he's given a rope to skip. Music is turned up: "I see that look in your eye . . .

"The bell rings to open the first round. Cooney opens with three thudding jabs. A right is followed by a left hook to the body, and Cooney's opponent already appears hurt. A left uppercut lands violently. Two tremendous left hooks connect in succession, and the opponent slumps to the canvas." A 36-year-old Ken Norton was counted out in 54 seconds.

That was 1981. Those 54 seconds earned Cooney his title fight with Holmes. Now, history could repeat. If Cooney catches Spinks, he will earn another title fight, with Tyson. A defeat and Cooney may disappear. After Cooney lost to Holmes, it took him 27 months to return to the ring. Even then, he returned to fight the never-renowned Phillip Brown in that boxing hub, Anchorage. Could the Eskimo settlement of Thule be next?

Not if something Cooney says is true. He's "had a great education in boxing. When I fought Holmes, I feel I was a better fighter than he was. I was just so caught up in what was written about the fight -- I got caught up in that whole thing." He made the cover of Time.

"It was a world-wide thing. It was a crazy thing. I had never experienced anything like that before. You kind of get shaky at times. But" -- again, he said it -- "it was a great education for me."

So he's grown up? Always Hurdles

In the next breath, he hasn't grown up -- it's as if he could never grow up as long as he boxes. A bachelor, he looked ahead: "Someday, when I grow up, I want to have a family. There's a lot of things I want to do, a lot of hurdles I want to . . . "

One thing is certain with Cooney -- there will be hurdles. Always were, always will be.

If his father -- a 6-foot-3 1/2, 220-pound small-time boxer, merchant marine, construction worker -- hadn't loved the sport so, he might not have set up a ring in the family's backyard on Long Island, in Huntington, for his four sons. (Gerry was No. 3; Arthur, known as Tony, and Eileen Cooney also had two daughters). In the backyard, Gerry lost his first fight, to a girl.

He might have known nothing would come easy. Before he had won a second Golden Gloves crown, he had gotten mad at his father; 18 then, he thought the father was pushing him too hard. As happens in families, including big Irish ones where members love, and sometimes hurt, others, Gerry moved out of the house. In time, he came to know what it was his father wanted: the son to have a life better than his, and to know that he could.

He learned that before his father died, in 1976. After that, Geraldine Gorman, his English teacher at Walt Whitman High School, told him something he could understand better than he ever could Shakespeare.

"She said that for at least a year your mother's going to need someone to talk to," said Cooney. He was in his suite, high above the Boardwalk. The TV was on; the screen was the size of a small wall. He wasn't watching it, he was intent on remembering Mrs. Gorman. "I was very fortunate. She said that even if you don't want to listen to your mother, you're going to listen. You're going to have to listen." He listened to the teacher, then gave up boxing -- for the first time -- to listen to his mother.

Eventually, he returned to the ring. Turning pro, he signed with two Long Island real estate men as his managers. Rappaport is still around. So is trainer Victor Valle, 67, once a quality featherweight (46-1) whose career was stopped by soft hands. The Puerto Rican-born Valle considers himself a disciplinarian. "Gerry's father was a strong-charactered man, like me," he said. "It's as if the spirit of his father was sent to me to guide him for the rest of his life."

Years ago, Valle tried to get Cooney to think he was a ring killer. Just like Cooney's father had tried. What they had was this big guy, a decent fellow, a fighter with tender heart and small hands, neither requisites for a ring killer. He'd try. He'd go all out against sparring partners, but this led to few sparring partners and many gym injuries for Cooney. There had to be an easier way.

"When I was growing up" -- he's always talking about "growing up" -- "I was into every minute of every round in the gym. I was always going hard. As you get older, you realize when you work at that intensity something has to give. So I don't punch as hard as often. You have less chance for injury."

That being the case, he'll never injure his right hand. He's never had much of a right, and doesn't throw it often. His left to the body sets up his left to the head. Converted from a southpaw by his father, Cooney has long appreciated the value of a left to the body. Once, he saw his oldest brother, the one recovering from the drug problem, use a hook to the body to drop an alley opponent. Cooney has not forgotten. Ken Norton knows.

Then came Holmes. In advance, Time's cover had Cooney and Sylvester Stallone peeking from behind their gloves. "Heavyweight Hits! Boxing Scores One-Two Punch at the Box Office." The shame of the Holmes fight was, contended Cooney, he got all confused by so many people giving so much advice.

Since then, he's saved his brother from possible suicide and answered his mother's every grieving call, day and night, through the bad times. He's fought less than seven rounds, scoring three knockouts. His record is 28-1, but it's taken 10 years. He said he's wanted to stay independent, outside the Don King-promoted HBO heavyweight unification series. If few opponents were available, causing Cooney frustration, waiting has its rewards. He grossed $10 million for fighting Holmes; he'll make $5 million for fighting Spinks.

No matter what happens, he'll have his millions and he'll have time to care; some day, he said, he wants to advise boxers, telling them to be independent, "of a way," Rappaport put it, "you can wind up your career with security instead of broken spirits and being broken financially."

He may get married. For now, he lives just a few blocks from the home he grew up in. His younger brother, Steve, lives with him, in a duplex. He visits his older brother, who's getting better, and listens to Eileen every night at dinner, and drops in on Mrs. Gorman. He may still feel like a kid, but they know differently. He's Gerald Arthur Cooney, their champion, all grown up.