As "North Dallas Forty," a film that portrays the world of professional football as violent, lascivious and narcotic, plays to big crowds in theaters throughout the country, three former pro players who had key acting and advisory roles in the filming find themselves less than boffo in the National Football League, Three of them -- Tommy Reamon, Tom Fears and Fred Biletnikoff -- have been completely severed from football.

Reamon, a running back who was cut in training camp by the San Francisco 49ers, claims he has been "blackballed" by the NFL because of his participation in the movie, which began filming last December, Reamon also claims there is "a conspiracy," directed by the NFL against himself, Fears, Biletnikoff and John Matuszak of the Oakland Raiders. NFL owners and management are known to be upset with the themes of "North Dallas Forty," based on the book by Peter Gent, a former wide receiver for the Dallas Cowboys.

Pete Rozelle, the NFL commissioner, yesterday called the conspiracy suggestion "absolutely ridiculous," He also said, "the Cowboys did not like the book, nor did a lot of us in the league." Rozelle has not been the movie.

Reamon, at best a reserve in his NFL career -- the Redskins cut him in preseason 1978 -- was one of the 18 active NFL players involved in the filming. He played a supporting role, a speaking role as a character seemingly based on Bob Hayes, the former Cowboy All-Pro receiver who was recently sent to prison after pleading guilty to selling cocaine.

Fears, a member of the Professional Football Hall of Fame, was an All-Pro receiver with the Los Angeles Rams and coached the New Oreleans Saints. He advised on the filming. Recently he began a scouting service for professional football teams, but the three NFL teams that subscribed to his service dropped him last month, after "North Dallas Forty" opened.

Biletnikoff, for years in All-Pro wide receiver for Oakland, was the technical adviser to the star of the movie, Nick Nolte; he coached Nolte on pass receiving. The Raiders dropped Biletnikoff last May.

Frank Yablans, producer of "North Dallas Forty," said that his "honest opinion is that there isn't a conspiracy." But after cataloguing the situations facing Reamon, Fears and Biletnikoff, and after pausing for emphasis, he said, "But I'd call them pretty strange coincidences . . . my feeling is that football is such a business that if a player's important to a team, he plays. But with a borderline player, well, this movie might be the catalyst for a team to get rid of him."

"Good football players play in this league," Rozelle said. "Anyone who knows the 28 managements in the NFL knows they couldn't conspire on anything. It is totally untrue.

"I can't say that some clubs in their own judgment made decisions based on many factors, including that they did not like the movie," he added, "particularly a team directly involved, like Dallas.

"But, when you talk about blacklisting, you're talking about a league conspiracy and that's ludicrous."

Rozelle, who had not heard about the termination of Fears' scouting contracts, said, "If Tom Fears called me and said, 'I think I'm being blacklisted throughout the league,' I'd make a few calls and call him and tell him what I found out. But I'm sure he's not being blacklisted."

Rozelle said that Fears' problem might stem from "a few unfortunate remarks he made about one of the teams he was working with, the Houston Oilers."

In an article printed last month in the San Angelo Standard-Times, Fears was quoted as saying that the Oilers had only "four gold nuggets" on its team while the Steelers had 19.

Reamon, Fears and Gent said they had heard that Matuszak, an active NFL player who played a major role in the film, was having trouble negotiating a new contract with his current employer, the Oakland Raiders. Matuszak, once the No. 1 draft pick of the entire NFL, portrays an offensive lineman on the North Dallas Bulls in the film. In a key soliloquy toward the end of the film his character accuses a North Dallas assistant coach of having no understanding whatsoever of players and their motivation in playing pro football.

"It's definitely a movie with something to say," Matuszak said yesterday from Oakland. "There's some truth and some distortion, but it's just a movie. There'a a lot of Hollywood in there."

Matuszak said he knew nothing of a conspiracy, terming it "bull." Matuszak is a starter for Oakland, an important player -- not the kind to be cut. For him to go, a conspiracy would have to be in effect. He said he wanted to set the record straight because other people have asked him about this. "No pressure from anyone," he said. "I'll tell you like it is. I haven't had any problems. That stuff about having trouble negotiating is dead wrong. I negotiated two months ago and signed a three-year contract. I'd be the one to know, wouldn't I?"

Gent said he had no doubt there was at least a conspiracy directed toward the book and the movie by the NFL. "It's been going on for a long time," he said. "It starts in Rozelle's office. Rozelle and Tex Schramm (Dallas president) are very tight -- very tight. Schramm hired Rozelle into football as an assistant P.R. man with the Rams. Rozelle is Schramm's man."

Gent told a story about the promotion of his book when it went into paperback sale in 1974. He said that New American Library filmed a television commercial to run on all three networks in conjunction with the opening of the football season.

"Two networks refused to run it, and the third ran it only once," Gent said. "When we asked them why, they said it was because there was a hypodermic needle in the commercial, and that was distasteful."

Gent believes that the networks, by virtue of their $500 million contract with the NFL for broadcast rights, are full partners with the NFL. "You've got to consider how much money is involved," Gent said.

Reamon did not understand why he was cut by the 49ers. He said that O. J. Simpson had told him he was one of the best backs in camp. It was only afterward that he considered the possibility of conspiracy. "I didn't know what was going down, but look, I played Bob Hayes in that movie -- and you know what happened to him. I know Rozelle's behind this. Schramm and Clint Murchison (Dallas owner) are powerful men, man. I could be the best back in the whole world, and none of these teams will even let me close. I'm being blackballed. And I love this game, man. All I want to do is play."

Like Reamon, Fears has "not been doing much" since the picture came out.

"You can only guess at these things," he said. "But I was doing work for three clubs in the NFL and I'm not anymore. It could be connected with the picutre. But I'm not saying it is. There is no way to prove it."

Fears has spoken with Reamon and has heard about Biletnikoff's problems. "It filtered down to me," he said. "I took it with a grain of salt until it happened to me. I was working in an advisor situation with the Packers, the Redskins and the Oilers. I had agreed to an agreement with 'Bum' Phillips. Within a week, all three fell out on me.

"I'm very upset. I don't have anything concrete, but it makes you think there's something to it."

Part of Fears' job as technical advisor was to help line up professional football players for the film. One of his first stops was Dallas.

When he arrived, Fears telephoned Schramm, "a good friend."

Fears' friend was "irate."

Fears said Schramm "was not in favor of the Cowboys doing it. When I called him, he asked me not to ask any more players to participate I could understand that."

Parts already had been offered to defensive end Harvey Martin and linebacker Thomas Henderson. Neither appeared in the film.

"They read the script," Schramm said. "And they turned it down."

Yablans suspects the Cowboys pressured Martin into refusing the role. Yablans said Martin read for the part that Matuszak ultimately played, "and he showed real talent. We agreed to pay him $1,500 a week plus expenses, but he didn't show up on the day he was supposed to, Feb. 26. We tried calling him, but he never returned the call. He showed up once the filming had started and tearfully explained that it was in his best interest not to be in the movie. I didn't press him on it, but it was obvious he'd been pressured and that it came from Dallas."

Henderson, the Cowboy linebacker known as "Hollywood," has said that he refused a role in the movie. But Yablans said that Henderson wasn't offered a speaking part. "He read for (a speaking role), but quite frankly, he didn't have the talent . . ." Yablans said Henderson could have acted in the film in a nonspeaking part.

Henderson is not talking about the movie. Although he has seen it, he said, "I have no comment. I just couldn't be honest about it."

Henderson said he decided against appearing in the movie because he realized, "It wouldn't be good for me, for my personality, for my standing with the team and with the NFL. I'm smarter than that.

"A skin film would be better than that."

Yablans said that he had received no pressure of any kind from the the NFL in the filming. The Houston organization and the Los Angeles organization, he said, were "very cooperative." Houston was going to allow Yablans to film on its facilities, and Yablans said the only reason that he chose, instead, to film at the Ram facilities was "because it was cheaper to do it in L.A."

The Dallas organization, however, "was totally uncooperative," according to Yablans. "First they said we could film there, then they refused. I never talked to Tom Landry (Dallas coach) or Clint Murchison, and they didn't put any pressure on us, but in my one conversation with Schramm he told me that he'd heard the film was laced with sex, sex with the players, even sex inside the management. I assured him that was false, that it wasn't laced with sex, but Dallas wouldn't allow us to film there."

Two months before the film was released, Biletnikoff, a 36-year-old receiver, was released by the Oakland Raiders.

He has not been contacted by any other team. "The only thing I can say is I haven't heard anything. I haven't heard from one club in the NFL, which, I though was kind of strange."

Schramm did not want to see "North Dallas Forty." But members of the Cowboy staff persuaded him that he should. They knew he was going to be asked about it.

Schramm, admittedly apprehensive when he entered the theater, later said it was not as bad as he expected. Still, he said, "It's a totally dishonest portrayal of professional football," one, he added, which the Cowboys "resent."

Reached in Tampa yesterday, Ed Garvey, executive director of the National Football League Players Association, said that he had heard nothing about a conspiracy. "Nothing in terms of discrimination, either," Garvey said.

But the possibility of conspiracy seemed to intrigue him, and he said, "Whenever, there's a conspiracy of this level the only two people who run the league are Pete Rozelle and Tex Schramm. I'm sure Clint Murchison and Tom Landry aren't very happy with this movie. I'm certain Pete Rozelle is furious with it."

Garvey said he liked the movie very much. He said he wrote Gent to congratulate him and invited Gent, Mac Davis and Nick Nolte to address the NFLPA. During the course of the film, Nolte, who plays Phil Elliott, wide receiver patterned after Gent, wears a T-shirt that says "No Freedom/No Football/NFLPA." That, of course, was the slogan the players association adopted in its strike five years ago.