An NCAA committee studying possible modifications of Proposition 48 will not make any recommendations until the end of this month, Wilford Bailey of Auburn University, NCAA secretary-treasurer and committee chairman, said yesterday after a meeting here.

But sources who attended the meeting of the Special Committee on Academic Standards said the committee is leaning toward recommending the use of an Eligibility Index Formula, by which lower test scores could be offset by a higher grade-point average as a means for achieving first-year eligibility in Division I.

The committee also is considering whether to recommend a waiver exempting institutions at which less than half of all incoming students score below the minimum test score requirement of Proposition 48, which is 700 on the Scholastic Aptitude Test or 15 on the American College Test.

Taken together, these modifications apparently would solve two major issues raised when Proposition 48 was passed at the 1983 NCAA convention, to become effective for the 1986-87 academic year: They would eliminate the arbitrary cutoff test score to be eligible to play as a freshman. They would reduce the disproportionate impact of Proposition 48 on black athletes, especially those at the 16 Division I institutions whose enrollment traditionally has been predominantly black.

Samuel L. Myers, executive director of the National Association for Equal Opportunity in Higher Education, declined comment, saying that participants at the meeting had agreed to let Bailey serve as spokesman. Bailey said the committee had decided not to discuss its work until recommendations, if any, are formulated, because of the emotional aspects of the issues.

Bailey said the committee, which will conclude two days of meetings today at the Twin Bridges Marriott, will meet here again July 29. Recommendations would have to be made then to be considered at the NCAA Council's summer meeting Aug. 14-17. Modifications must be approved by the NCAA membership at the annual convention in January in New Orleans or Proposition 48 will go into effect as is.

Reform leaders in intercollegiate athletics have favored an indexing plan since the American Council on Education was instrumental in lobbying for passage of Proposition 48 at the 1983 convention. But the waiver might not be as readily acceptable because it is viewed "by most as highly undesirable in terms of educational philosophy," according to a confidential briefing paper published by the committee.

Under Proposition 48, only 18 percent of all black male athletes entering Division I schools in 1982 would have been eligible as freshmen. Under an indexing plan devised by Robert Klitgaard, a professor at Harvard, 51 percent of all black male athletes and 94 percent of all white male athletes would have qualified.

Some black educational leaders are known to oppose indexing without a second option because too many black athletes still would not qualify.