The two-day meeting here of an NCAA committee studying possible modification of controversial Proposition 48 had just concluded yesterday when Gwen Norrell of Michigan State told her fellow committee members, "I leave here feeling much better than I did coming in."

Coming in, there was wide concern the committee would be unable to rectify the inequities of Proposition 48 as to black athletes, without eroding its basic standards. The rule, to become effective for the 1986-87 academic year unless modified, requires a minimum test score (700 on the Scholastic Aptitude Test or 15 on the American College Test) and a 2.0 grade-point average in a core curriculum of 11 high school or prep school academic courses as a requisite for first-year athletic eligibility.

After hearing from representatives of various segments of higher education Monday, the committee decided on a two-pronged approach. Members will study the feasibility of using an Eligibility Index Formula that would allow lower test scores to be offset by a higher grade-point average. They also will consider granting a waiver to institutions at which at least 50 percent of all entering students have test scores below those required in Proposition 48.

Specifics will not be determined until the committee meets here again July 29. Then it is expected to make its report to the NCAA Council at its August meeting. The NCAA membership would have to approve any modification at the annual convention in New Orleans in January.

"The committee tentatively has identified a framework, the essence of what we think will be a logical and appropriate conclusion and the basis for recommendation," said committee chairman Wilford Bailey of Auburn, NCAA secretary-treasurer. He declined to discuss details.

"Everybody came out with a good feeling," said Eric Zemper, an NCAA staff member.

That good feeling is a relief to the leaders of reform in intercollegiate athletics. They privately have been worrying that a divisive floor fight in January over fine-tuning Proposition 48 could wipe out the momentum the reformers established at last month's special NCAA convention.

Pending modifications "are academically reasonable and defensible," said Shelly Steinbach, general counsel for the American Council on Education, which led the 1983 fight to adopt Proposition 48.

There are several indexes being considered. The one that has gained the most publicity since passage of Proposition 48 was devised by professor Robert Klitgaard of Harvard. Called Pred 200, its formula makes a 2.0 grade-point average and a 700 SAT score equal 1,100 (700 plus 200x2.0). Thus, if an athlete scored 640 on the SAT, for instance, he would need a 2.3 grade-point average (640 + 200 x 2.3 = 1,100) to be eligible to participate.

Still to be determined is whether an Eligibility Index Formula would include an acceptable minimum test score, "thus limiting the extent to which the lower test score could be offset by higher grade-point average and, therefore, limiting the effect of grade inflation," according to a committee briefing paper.

The extent of the institutional waiver also must be clarified. Samuel L. Myers, executive director of the National Association for Equal Opportunity in Higher Education, referred to this modification as "an option" during his presentation to the committee Monday.