v. hat his mother once feared would happen has happened to Leon Spinks. He is the heavyweight boxing champion of the world - after only eight pro fights.

"The main thing that concerns me," Kay Spinks said not long before her son's stunning upset of Muhammad Ali Wednesday night, "is not the money, but how he takes success. I want him to have the right type of peace of mind."

Spinks, a child of a depressing public-housing project in St. Louis, said he learned to fight "by defending myself. From 9, 10, 11, 12, all the way to 16. I used to get beat up every day. I was pretty quick on my feet."

How fast could he run 100 meters? a man from England wanted to know.

"Two seconds if I was being chased."

It seems much to early to develop any sort of image of Spinks as champion. His prefight goals were modest and his postfight goals were "to take a boat trip on water" and visit some foreign countries.

"I was raised in a big project, something like 25 buildings 11 stories high," he said. "The buildings started to rot and the plumbing got bad, so people started moving out." Later, the project was torn down.

Of his long-term ambitions, Spinks said a day or so before Ali fight: "I'd like to get a club of my own. I'd like to be a bartender. Yeah, I'm serious. That shocks you, don't it? I'd like to wait on people. I love to talk to people."

This morning, he hardly was comfortable before perhaps 75 reporters squeezed into a room the Hilton rents for two, although sudden changes in subjects and assorted legalese might have made the most articulate man suddenly thrust into such a position ill at ease.

Much of the press conference consisted of rambling thoughts, not entirely his own fault. SUch as: "I want to be the best . . . 'I want to retire (as champ) when I'm young . . . I'll take everything step by step . . . This all goes to show that if you try you can make it . . . He (Ali) didn't think I was as strong as I was.

His mother had talked of her reluctance to encourage him to take the fight from Ali when it was first proposed and her gradual change in attitude.

"(At first) I thought it was the most terrible thing I every heard of. I prayed hard. I asked Him to stop it. Muhammad Ali is kinda big to me. I told him (Leon) that I forbid it, but he didn't pay any attention to me." She laughed.

Mrs. Spinks usually may be seen near ringside at Michael's and Leon's fights, clutching a Bible and acting more like a fan than a mother.

"My kids get in the ring and I'm not even here," she said. "I forget people are here. Sometimes I box right along with 'em. I get a chance to holler like I'm 14 or 15 years old.

"I still look at this as a form of entertainment. I told Leon to hold out 'till the very end. I said 'Hang on, Leon, hang on. There's no reason to knock anybody out.'"

Several floors away, the former champion, Ali, was quiet and dignified, although still clinging to the notion that he could wrest the title from Spinks.

He admitted defeat, and spoke of the late Hubert Humphrey, how he admired his cheerful appearance even though he knew he would die.

To someone who still called him champ, Ali said; "You don't have to call me champ to be my friend."