ATLANTIC CITY -- The money made him do it. Michael Spinks didn't really want to be a boxer but, in the beginning, it was safer in the ring than in his St. Louis housing project. After that, people kept shoving millions of dollars at him to fight. Monday night, for fighting 15 rounds or less with Gerry Cooney, Spinks will make $7 million.

Who in boxing history has been a more reluctant warrior? Cooney's not reluctant -- he's got a hundred reasons why he's only fought seven rounds in five years, leaving him dropped from sight, the heavyweight division's answer to chess' Bobby Fischer. It's not like Cooney didn't want to fight. But Spinks, he'd have been happy being Cooney the last five years, essentially retired.

Spinks owns a 30-0 record -- the first light heavyweight champion to become heavyweight champion -- yet goes into a fight thinking he might lose, acknowledges fear, admits being tired of having bigger sparring partners pound on him. But if he does not have a stomach for boxing, he does have the heart.

When asked what his advantages would be against the larger Cooney, Spinks replied, "My speed and my ability to move in and out and" -- pausing to place his hand over his heart -- "my big left ticker."

If he were only bigger and stronger, Spinks said. He's 6 feet 2 1/2, about 200 pounds -- at age 30, he's finally got some weight. But not enough to suit him.

"Even though I'm a heavyweight, I'm probably the smallest heavyweight out there," he said, "and I have to admit, boxing all these big guys all the time, it isn't like lying on the beach or a walk in the park. It's work. It's serious work.

"It leaves me with an attitude of" -- and here he laughs -- "I mean, really, really wishing, hoping that overnight I just wake up and I'm all that I would ever want to be as a heavyweight, weighing maybe about 250 and punching like a Mack truck."

Can you blame him? Cooney is 6 feet 6, 230 pounds, and Spinks' sparring partners, Tebin George and Pete Ludwinski, are, respectively, 6-7, 235, and 6-6 1/2, 232. Spinks dreams of being bigger, not so he can be the King Kong of boxing instead of the self-effacing fellow he is, but merely "to keep these big guys off of me."

If he weren't supposed to be a heavyweight, Spinks would be plenty big. He has a long body -- long legs, long arms when he's stretched in a chair. This was upstairs in Trump's Castle, a hotel and slots emporium. He spoke slowly, plaintively, like a voiceover on a sad song.

"I can't complain. I'm through all the workouts for this fight without getting knocked down or knocked out. It's painful, but I'm makin' it. I'm boxing much taller guys. Really tall guys, and it's really, really difficult punching on these guys the way I would like to. And that tends to frustrate me a little bit. I come into the gym in the mood to really work, really execute in there, and I can't do it."

So how can be beat Cooney?

"I felt more terrified to lose as a light heavyweight than I do now as a heavyweight," he said.

A boxer terrified?

"I'm telling you. Honest to God. It's really strange. I don't know why, these guys are punching six times harder than the guys in the lower division. I guess to lose to someone who weighs the same as you is a serious blow.

"I'm not the type to be making excuses but, you know, he outweighs me by 30 pounds. You say, what the heck. When I feel this way, I try to get rid of this in my head. 'C'mon, now, why are you thinking like this?' "

Could his handicap, even against someone Cooney's size, be more of mind than body?

"I think the best way to try to win this fight is take it down the road apiece." Do what he calls his "one, two, three" -- jab, jab, move.

"I can't go toe to toe with Cooney -- at least I really don't know how well I could stand in there with him. If I had to, I really don't know.

"I want to win. I want to win in a very good fashion. But if I could, I would come out of the fight unharmed, unblemished." He laughed again. "Being a boxer, a dedicated gladiator" -- another laugh -- "you can't blemish someone without being blemished, I don't think.

"But I really would love to come out of it without a scratch." Leon Was First

In the beginning, it was Leon, wild Leon, Michael's older brother, who wanted to fight. Leon beat up on guys in St. Louis' Pruitt-Igoe, a crime-ridden housing project that public officials eventually conceded was a terrible failure. It was cleared and, in part, literally blown off the earth.

Leon Spinks was the toughest of the toughs in Pruitt-Igoe -- and Michael often paid for it. "Are you Leon's brother?" gang members would say to him. They were bigger and, like his recent sparring partners, they would pound him.

Leon's pro career has gone like cheap Fourth of July fireworks -- a little sparkle, then all fizzle.

Leon, as a light heavyweight, and Michael, as a middleweight, won Olympic gold medals in 1976. Then, after just seven pro fights, Leon won the heavyweight championship from Muhammad Ali. But seven months later, Leon -- today a journeyman -- lost the title to Ali. In the process, he lost the retinue of 70 he took to the ring that night. Leon walked away alone.

He turned back to Michael, whom he had turned into a face in his momentary crowd. Michael was always there -- because, if anything, Michael Spinks is like Gerry Cooney, his big family's father figure even though he, too, is a younger brother.

Cooney and Spinks are alike: large men who look able to suffer -- Cooney with a career of assorted ailments, Spinks with bruises from batterings by bigger men.

Cooney and Spinks, with their gentle exteriors but hard-bodied interiors that have let them be sources of strength -- Cooney helping see his oldest brother out of drug addiction, Spinks when his common-law wife, Sandra Massey, died in a car accident, the woman he's called "my first and only love."

Spinks' 6-year-old daughter, Michelle, still asks him about her mother, and about why he fights. Her grandmother in Philadelphia takes cares of her; she often sees her father, who lives in Wilmington, Del.

Spinks was crying over his lost love when he went to the ring to fight "The Camden Buzzsaw," Dwight Muhammad Qawi (at 5-6 3/4, a foot shorter than Cooney) for the unified light heavyweight championship. It was March 1983 -- two months after the crash on Philadelphia's Schuylkill Expressway that killed Sandra. But Spinks won in 15 -- just as he would twice against Larry Holmes.

Holmes, who took only three rounds to demolish Leon in 1981, had mocked Michael, but the younger brother could not be bullied, or even angered by Holmes -- when Holmes complained during the fight of being thumbed by Spinks, Spinks apologized on the spot, even though he didn't think he had thumbed.

It's apparent, Spinks is no ordinary man of the ring. In the midst of the first Holmes fight, he turned to his cornermen, who had been yelling instructions, and cried, "Shut up! I'm doing the best I can."

He has to admit, there's one part of boxing that's exciting -- "the victory, because of the way I take it. I never actually say to myself I won. No matter what. I say, it's not won until the bell sounds and they raise my hand in victory.'I Could Lose'

"I actually go into the fight with the attitude that I could lose. So when I win, it's a well-accepted victory. I've dealt with him in my mind. And I've given him his just due."

Spinks has scored 20 knockouts in his 30 victories -- he can hit -- but he thinks mostly of winning decisions. He likes to fight tactically -- but what's on his mind now is how Pinklon Thomas was booed during his recent fight with Mike Tyson, when Spinks thought Thomas was trying to fight tactically, before Thomas went down and out in six. Spinks wonders whether, while he carries Cooney "down the road apiece," trying to make him arm- and leg-weary, if the crowd will boo him.

"I'll be glad to get it over with. You go on and on for weeks and weeks wondering how you will win, if you'll win . . ."

There was a time when he enjoyed boxing. "Of course I did. I was a kid. Yeah, I still enjoy boxing, to a certain point. But the fighting and all the things you go through preparing yourself for a fight, that seems to annoy me every now and then."

In some ways he is trying to catch up with his past -- to a point, not back to Pruitt-Igoe. To when Sandra lived, to when he fought as a light heavyweight. The silver bracelet he wears tells not of the heavyweight title he once held -- the International Boxing Federation stripped him of its title because he chose to fight Cooney instead of its selected opponent. He wears a light heavyweight champion's bracelet.

In Trump's Palace, Spinks surprisingly has found the past, the small gyms of St. Louis and later Philadelphia. He's found his roots in a most unlikely place -- a glass cube out front that once was a flower shop. The curious look through the glass.

It's hot in there, but Spinks doesn't mind. A blond woman in a white dress and red "Miss Knockout" sash parades past him, but he doesn't look her way. His mind is somewhere else.

As he said, "It's a very, very small room. I mean, the public can't even get in there. But it takes me back to the way it really was, back in my home. We didn't train around a bunch of people. If you were not a boxer yourself, you couldn't sit around. No women allowed, sitting out there watching you. It reminds me of the way it was."