"I can't tell you how delighted I am," pronounced bill Bradley, the football player. "It's like going from Class B ball to Class A."

Where safetyman Bradley is going is from the Philadelphia Eagles to the Minnesota Vikings. The old Texas Longhorn paid his dues by knocking heads home-and-home with the Redskins, Cowboys et al in the NFC East since 1969, holding on field goals and extra points, occasionally taking over the punting and serving as defensive cocaptain. Now he gets to do it in the renowed, but Viking-dominated, "black-and-blue" division.

Bradley, led the NFL in pass interceptions in 1971 and '72, only man ever to do so back-to-back, and his total of 34 is the Eagle record. He picked off only two last year -- but one was against the Vikings, with a touchdown-setting-up 52-yard runback. George Allen indubitably is glad to see him out of the division. . .

The Vikes gave up an undisclosed 1978 draft choice yesterday for Bradley saying they can use help in the secondary because their all-time interceptor, former Redskin Paul Krause, is 35 and Jeff Wright is coming off knee surgery. The question now is who needs quarterbacking help enough to pick up Mike Boryla who not only feel from favor with the Eagles last fall but now, it seems, has fallen clear off their roster.

It's just been learned that the Eagles failed to send Boryla the NFL-required option renewal letter as required by May 1, apparently making the off-and-on first-stringer a free agent because the three-year contract he signed with Philadelphia in 1974 has expired. The Eagles say the situation is "darn complicated and darn technical" but they believe he is still theirs. But never mind, "A mutual agreement between both parties has enabled us to work out a procedure for trading Mike. We expect Mike to be traded, and we expect both the Eagles and Mike to receive fair compensation" . . .

When Steve Cathen suffered a fractured wrist and all-around banging-up in a spill at Belmont Park, word was that he'd be in a cast for six weeks. But on Thursday, one month from the day of the accident, Cauthen comes back, scheduled for four rides at Belmont. The 17-year-old apprentice with the 275 wins this year is due in New York from his Walton, Ky., home to exercise horses this morning and Wednesday. He said before leaving. "I'm just going to go back and ride like I always did. I'm not going to change my style and I want to keep trying to learn" . . .

Will Seattle Slew, too race again sooner than expected? Following his Belmont Stakes triumph June 11, trainer Billy Turner and co-owner Dr. Jim Hill said Slew would be rested and taken to Saratoga in August for a possible start in the Travers. But now --wood.

Hollywood Park officials yesterday offered to boost the purse for the $200,000 Swaps Stakes for 3-year-olds on July 3 to $300,000 if the Triple Crown champ would fly out and give it a shot. And co-owner Mickey Taylor didn't say no. He said, let you know Wednesday. Will Silver Series, the colt that added the Ohio Derby to its Hawthorne Derby victory to back up those challenging noises from its backers, be there for the Swaps?

A load off the mind of Doug Flynn, the infielder traded from the Reds to the Mets in the Tom Seaver deal: his sister, Melanie Dee Flynn, 24, who vanished Jan. 26 giving rise to speculation of foul play, is O.K. A secretary at the Kentucky High School Athletic Association in Lexington, she missed a doctor's appointment and her car was found in an apartment lot in Lexington: police confirmed she spent March to June in Daytona Beach, Fla., no harm had come to her and the missing-person file is closed . . .

Nice to see Irish Gene Wells getting a shot at a boxing title, no matter how obscure, against Ralph Palladin in Cap Centre tonight after the letter we received from his Orlando digs a few weeks ago. Citing "legal entanglements" and "exhausted funds," Wells was soliciting help "to stave off the third and final knockdown in a courtroom battle for freedom." Couldn't be too bad a guy, he requested that "donations should not exceed $5."