Following three days of deliberations, a jury in Tampa, Fla., yesterday convicted Denny McLain, baseball's last 30-game-winning pitcher, of racketeering, conspiracy, extortion and cocaine possession.

The nine-woman, three-man panel, which listened to 350 hours of testimony, found McLain innocent on one count of conspiracy to smuggle cocaine.

Codefendants Seymour Sher and Frank Cocchiaro were convicted of racketeering and conspiracy. Joe Rodriguez was found innocent on a charge of conspiracy to smuggle cocaine.

McLain faces a maximum penalty of 75 years in prison and fines totaling $75,000. Sher and Cocchiaro could get 60 years and fines of $60,000, said Assistant U.S. Attorney Ernst Mueller, the prosecutor in the case.

McLain, who maintained his innocence through the four-month trial, was "devastated" at the verdict, said his attorney, Arnold Levine. "He's just shocked. He's concerned about his children and his wife."

McLain, 41, and Sher were taken into custody pending a hearing today before presiding U.S. District Judge Elizabeth Kovachevich to determine whether they can remain free on bond until sentencing April 19 . . .

John Blackwell, 38, of Los Angeles, a self-proclaimed "street warrior" claiming to be protecting Olympic athletes last summer by following their bus in an explosives-laden car, was sentenced to nearly five years in prison.