The group that shepherded the passage of the NCAA's controversial Proposition 48 is opposing major modifications to the rule.

"We need to remember that the purpose of the rule is not to maximize eligibility but to assure that the high-risk student is established academically before participating in athletics," said Bob Atwell, the acting president of the American Council on Education, in a statement released yesterday.

"Most of the people who were the original proponents of Rule 48, while open to reasonable suggestions for improving the rule, are not anxious to see it gutted," he said. "And it would appear that at least one of the NCAA committee's suggestions would have that effect."

If not modified, Proposition 48 would require a 2.0 (out of a possible 4.0) grade-point average in a core curriculum of 11 academic courses and a minimum score of 700 (out of 1,600) on the Scholastic Aptitude Test or 15 (out of 36) on the American College Test for first-year eligibility in college athletics. It is scheduled to become effective Aug. 1, 1986.

When the rule was passed at the 1983 NCAA convention, many black educators said it would discriminate against black athletes because the entrance exams were culturally biased. Research commissioned by the NCAA showed that 70 percent of black scholarship athletes who graduated after entering in 1978 would have been ineligible under Proposition 48.

The NCAA committee suggested three modifications, two of which would allow the test score to be used if a student does not have the core curriculum. Although Atwell was not available yesterday to clarify his statement, he apparently objects to circumventing the core curriculum.

"The definition of high risk varies greatly between institutions," Atwell said in his statement.

Atwell said many in his group favor giving universities a choice between Proposition 48 and other screening measures written specifically for their school and "based on a combination of tests scores and the grade-point average. But that approach is very different from simply dropping the test score altogether."

The NCAA committee's third suggested modification addresses this issue, but members of the committee and NCAA hierarchy are not in favor of it.