Buddy Ryan, the designer of the Super Bowl-champion Chicago Bears' defense, has signed as coach of the Philadelphia Eagles, team owner Norman Braman confirmed yesterday.

Eagles General Manager Harry Gamble said lengthy negotiations yesterday ended with Ryan signing a five-year contract.

A Bears spokesman said team president Mike McCaskey did not try to talk Ryan into staying in Chicago. Said McCaskey, "The bottom line was that Buddy wanted to have a chance to run his own organization. The money issue has a limit. And when we're talking about as much money as a head coach makes, there's got to be a limit" . . .

Also yesterday, the New Orleans Saints announced they are giving Jim Mora of the U.S. Football League's Baltimore Stars a chance to succeed at something that has defeated six other men in the past 19 years: to produce a winner as the team's head coach.

"In Jim Mora, we have a man who has won and knows what it takes to have a winner," said Saints owner Tom Benson. "He's won everywhere he's been. He's also the kind of person we need for our team, our fans and our city."

Fink said Mora's contract was for four years, "and that's one more year than I have." Mora said he would bring his entire staff of eight assistants from the Stars.

Mora, 49, replaces Wade Phillips, who coached the Saints to a 1-3 finish after his father, Bum Phillips, resigned in late November with the team 4-8. The 5-11 finish was the Saints' second worst in the Phillips' five seasons at New Orleans. The Saints fired Wade Phillips and most of his staff Jan. 22.

Excluding Wade Phillips and three other interim appointments, Mora becomes the seventh head coach since the franchise was founded in 1967. The franchise's record is 83-187-5; its best season has been 8-8.

Mora coached the Stars to 52 victories the past three years, including back-to-back USFL championships the past two seasons, first in Philadelphia and then in Baltimore . . .

A spokesman for a Richardson, Tex., bank says Dallas Cowboys halfback Tony Dorsett has paid off $121,500 in debts to the institution, which returned a repossessed auto to the player.

"The bank was paid in full," a spokesman for First City Bank of Richardson said. The bank returned the Pro Bowl running back's 1983 Mercedes Benz.

Last July, Dorsett missed 20 days of training camp while seeking to renegotiate his contract. He owed the Internal Revenue Service about $414,000, had yet to pay $250,000 in a divorce settlement and had lost $600,000 in a failed oil investment, officials said . . .

Two days after he helped the Chicago Bears win the Super Bowl, William (The Refrigerator) Perry was named winner of the balloting for the fourth quarter in the black-athlete-of-the-year competition.

The 308-pound defensive tackle received 160 points in the voting and joins the other quarterly winners in the competition for the $25,000 annual award: New York Mets pitcher Dwight Gooden, Los Angeles Lakers center Kareem Abdul-Jabbar and runner Valerie Brisco-Hooks.

The balloting is conducted by a panel of black sportswriters and sportcasters.