Craig Payne, a construction worker from Livonia, Mich., won the first boxing gold medal at the National Sports Festival today with a unanimous decision over Al Evans in a heavyweight bout. The silver medal went to Tyrell Biggs, who suffered a broken hand in winning a Saturday semifinal.

Joe King of Washington, D.C., won a split (4-1) decision over Danny Montoya of Salt Lake City in the 106-pound division and moved into one of the other boxing finals, all to be contested Tuesday night, against Bryan Jones of Philadelphia. Herb Bivalacqua of Marrero, La., advanced to the 119-pound final against Floyd Favors, the world champion from Capitol Heights, Md.

Greg Louganis and Bruce Kimball, tuning up for the world championships in Ecuador, finished one-two in men's platform diving. In ice skating, Eliza Spitz, who suffered a concussion during practice two weeks ago, won the dance competition with Scott Gregory, and Brian Boitano bounced back from opening-day exhaustion to win his second event in a row and bolster his lead in men's figure skating.

Tom Raunig and Carol Chilcoat won the men's and women's marathons, with Beth Dillinger of Blacksburg, Va., and Cynthia Lorenzoni of Charlottesville third and fifth, respectively, behind Chilcoat, a Seattle runner who covered the 26 miles 385 yards in 2:47:55. Raunig, of Great Falls, Mont., was timed in 2:14:11, a Festival record.

Alice and Margarita Smith, identical twins from Bethesda, Md., won the gold medal in synchronized swimming duet at the National Sports Festival. Both women swim for the University of Arizona.

The Payne-Evans bout, originally set as a semifinal, became a championship fight because of the injury to Biggs, the world amateur superheavyweight champion. "It felt kind of funny sitting there," said Biggs, "since neither had won a national title before. But I feel good for Craig."

Payne, 21, who has been fighting only 2 1/2 years, got the 5-0 decision for the three-round bout by connecting with hooks and right uppercuts.

"I stayed inside because he had the longer reach," said Payne, who weighed 220 pounds to 204 for Evans, 27, of Chicago.

In the diving, Louganis of Mission Viejo, Calif., took his second victory of the Festival when he won the 10-meter platform diving with 640.53 points on 10 dives to 615.65 for Kimball of Ann Arbor, Mich