Willie Mays' separation from baseball has ended. He has rejoined the San Francisco Giants, who shocked him with a trade 14 years ago, in a job which will start with spring training coaching. He will carry the title of special assistant to the club president/general manager, Al Rosen.

"It's a day I've been looking forward to for a long time," said Mays, the hall of famer who has been out of baseball altogether since 1979 because of a decision by then-commissioner Bowie Kuhn. Over the last six years, "My wife knew that every day I woke up I wanted to be part of a ball club."

Mays, 54, ended his playing career with the New York Mets in 1973 and then worked for the Mets in a job much like the one he's taking with the Giants, which will involve mostly public relations work during the regular season.

In 1979, Kuhn ordered Mays to disassociate himself from the game because of the p.r. work he agreed to do for an Atlantic City hotel-casino.

Rosen, then an executive with Bally Enterprises, was the man who hired Mays in 1979. (Even now, Mays will continue in a goodwill capacity for Bally.)

Peter Ueberroth, who succeeded Kuhn as commissioner, declared last March that Mays and Mickey Mantle, similarly banished, could again work in baseball. And now, said Ueberroth, "all of us in baseball share in his happiness." . . .

Left-hander Geoff Zahn of the California Angels has turned down an invitation to spring training and retired. To go with his 13-year record of 111-109 with the Cubs, Dodgers, Twins and Angels, Zahn, 39, leaves a remarkable statistic: no stolen bases allowed in his final 292 2/3 innings.