Presidents and chancellors of NCAA Division I colleges left a special convention in New Orleans last week feeling so much momentum in the movement to reform intercollegiate athletics that they are sure controversial Proposition 48 can go into effect next year without modification.

"I'm convinced if a vote had been taken at that meeting, 48 would have been affirmed very readily, and that worries me because some fine modification still is in order," said John Slaughter, chancellor at the University of Maryland and Division I vice chairman of the 18-month-old NCAA Presidents Commission.

Proposition 48, requiring minimum test scores (either 700 on the Scholastic Aptitude Test or 15 on the American College Test) and a C average in a core curriculum of 11 subjects for first-year eligibility, was passed after an emotional floor debate at the 1983 annual convention, to go into effect in August 1986. But, 29 months later, a compromise has not been reached on fine-tuning that satisfies both reform leaders and leading black educators and civil-rights leaders, who say the test-score provision would be unfair to black athletes.

According to a study commissioned by the NCAA, six out of every seven black male basketball players and three out of every four black football players who received athletic scholarships at Division I-A institutions in 1982 would not have qualified if Proposition 48 had been in effect. In addition, more than one out of every three white male basketball players and just under one out of every two white football players would not have qualified.

Reform leaders are facing a dilemma. On one hand, they are concerned that, if they modify Proposition 48, they will appear to be capitulating and will lose momentum. On the other hand, implementing Proposition 48 without fine tuning could make the annual convention in January a bitter, racially divisive event that wrecks the reform movement.

A Washington Post poll of Division I presidents done before the special session showed that 59 percent favored implementing Proposition 48 without modifications.

An NCAA committee meets here Monday to try to reach what committee chairman Wilford S. Bailey, faculty representative at Auburn University and NCAA secretary-treasurer, hopes is a solution that is mutually acceptable and "does not significantly erode the educational standard" of Proposition 48.

"That's asking a lot for a modification," he said yesterday.

Joseph Johnson, president of Grambling State University, and Edward B. Fort, chancellor of North Carolina A&T, representing the predominantly black schools most affected by Proposition 48, say they are going into the meetings with an open mind.

But Johnson, who also serves as chairman of the board for the National Association For Equal Opportunity in Higher Education (NAFEO), said, "They do feel they have the momentum. But I don't think a lot of people will take it (as they did) in '83, lying on their backs, rolling over and accepting it.

"We may not win it. But we will make people aware of what's going on out there. I'm chairman of the NAFEO board, and we don't feel we have anything to lose. They may feel that way, but this is the way we feel. That's the beauty of athletics. Sometimes you think you have the momentum . . . but you can't underestimate the underdog."

Slaughter says he does not have a suggestion for fine-tuning Proposition 48. But he does have an alternative: repeal freshman eligibility, which would make Proposition 48 moot.

Slaughter said declaring freshmen ineligible would send positive signals to the public, too. "The symbolism of 48 might mean a great deal to some people," he said. But repealing freshman eligibility "would indicate the universities are concerned that their athletes are students first. Having freshmen eligible sends the wrong signal, that you are exploiting athletes for all the time they're on the campus. Properly presented, it would not kill the momentum" of New Orleans.

Many presidents favor repeal of freshman eligibility, but insist it is economically unrealistic. Shelly Steinbach, general counsel of the American Counsel on Education (ACE), predicted such a proposal would be defeated in January on "sheer hard-core economics."

Slaughter says that additional cost is an issue "that hasn't been answered . . . It may not be as much of a problem as many people think it is. It's a matter that the Presidents Commission will be taking up."

Proponents of freshman eligibility cite a recent study by the American Association of Collegiate Registrars and Admissions Officers (AACRO) showing that athletes are not adversely affected academically by playing varsity sports as freshmen.

The committee meeting here Monday will hear from representatives of NAFEO, AACRO and ACE, as well as the Educational Testing Service and the American College Test. The Rev. Ed Glynn, president of St. Peter's College who will represent ACE, says he will support an indexing plan that allows for a lower test score depending on the grade-point average.

A similar plan offered by professor Robert Klitgaard of Harvard would have qualified 51 percent of black football and male basketball players and 94 percent of their white counterparts in 1982. A plan by a previous NCAA committee to use either the test score or the core curriculum as a standard was not approved by the Presidents Commission.

Bailey said another meeting is likely before the committee makes any recommendation for the NCAA Council to consider at its August meeting.