ROCKY MARCIANO -- BIOGRAPHY OF A FIRST SON. By Everett M. Skehan. Houghton Mifflin. 396 pp. $10.95.

At hand is the story of another Rocky and this one does no more to elevate the perception of the sport of boxing above a sordid subculture than the other.

Marciano, incidentally, was the hero of the fictional Rocky Balboa in the recent Oscar-winning film, written and acted in by Sylvester Stallone, the Itallian Stallion.

The difference is that Marciano did make it from an uncoordinated "face fighter" to become the only world heavyweight champion to retire undefeated, after 49 bouts.

There is a topical analogy to current news. The Brockton, Mass., Blockbuster, who was killed in a plane crash in 1969, is quoted as charging his manager, Al Weill, with skimming off $10,000 from the promotional profits of a bout and not telling Marciano about it.

Marciano's daughter is cited as having heard that a Mafia figure offered the champion $2 million to lose to Don Cockell.

Marciano's admirers will be disillusioned when they read of him being widely regarded as "cheap," stooping to defrauding telephone coin boxes after he made his bundle, and "using" people.

The champion's mother is reported by author Everett M. Skehan of the Worcester, Mass., Evening Gazette, a Brockton native, as having received a threat that her son would be shot if he came home to celebrate after he knocked out Joe Louis.

Police reportedly traced the letter to a 13-year-old schoolgirl dismayed by the beating Marciano had given Louis, although Marciano took time in his dressing room to write Louis a note paying his respects and offering condolence to the former champion.

Ironies developed. When Marciano was killed, Louis attended the services and said, "Something's gone out of my life.I'm not alone, something's gone out of everyone's life." He bent over and kissed the casket.

Joe Frazier displayed a sense of dignity when a reporter asked how he thought he would have made out against Marciano. "Excuse me, mister. I'm here to pay my respects to one of the greatest champions ever. If you want to ask them (sic) questions, you come down to Philly next week."

The usually impassive Sonny Liston said, "This man was one of the greatest champions ever. He refused to accept defeat. And nobody beat him."

Beau Jack: "When I was down on my luck Rocky made it a point to look me up."

Because of those sentiments, it may be the more distressing to read in Skehan's book a posthumous quotation ascribed to Marciano in a colloquy with a Brockton friend Eugene Sylvester, about a report that Marciano was going to fight Louis.

"Rock, are you gonna fight him?" Sylvester asked.

"'Yeah,' Rocky said. 'It's all signed, Euey.'

"'Rock, this guy's awful big and plenty tough,' Sylvester said. 'But I know you can beat him Right?'

"'I'll never lose to a nigger, Euey,' Rocky allegedly said."

Author Skehan's use of the word "allegedly" in what is a quotation that cannot be checked with the late champion neither figures to acquit the author nor to ease the minds of others.