The overwhelming majority of America's Roman Catholic bishops are "basically in agreement" with a proposed pastoral letter condemning nuclear warfare, according to a straw poll reported yesterday.

A total of 195 bishops said they were "basically in agreement" with the document, 71 said they had "major reservations" and only 12 indicated "basic disagreement" with the 110-page paper, the main item of business at the annual meeting here of the National Conference of Catholic Bishops.

About 230 bishops responded to the straw vote, taken Monday by a conference committee, and some registered basic agreement while also indicating major reservations.

"The way I read the poll findings , we would vote for the document now" if it were put to the test this week, said Auxiliary Bishop Thomas J. Gumbleton of Detroit, a member of the six-man committee that drafted the complex statement.

At this stage, however, leaders of the hierarchy are more interested in producing a position paper that reflects the fullest possible consensus than in rushing it to a vote.

The present timetable tentatively calls for one or perhaps two more revisions of the paper, based on the bishops' criticisms, and then presentation for final action at a special meeting in Chicago in early May. Agreement by two-thirds of those voting is required for passage.

In the vote report released yesterday, the section of the pastoral drawing the most "major reservations" dealt with "theological principles and moral conclusions regarding nuclear war and war preparedness." The category dealing with the document's length and style raised problems with substantial numbers of bishops.

The pastoral has drawn theological and political fire, since it is the most comprehensive attempt in the nuclear era to adapt to nuclear warfare the just-war criteria laid down centuries ago in the writings of St. Augustine.

The pastoral rules out any first-strike nuclear attack as immoral and grudgingly condones nuclear deterrence as "morally acceptable provided it is used as a step toward progressive disarmament."

The document raises, but does not definitively answer, questions about the morality of retaliatory nuclear strikes. It says only that "under no circumstances may nuclear weapons or other instruments of mass slaughter be used for purposes of destroying population centers or other predominantly civilian targets."

Archbishop Joseph L. Bernardin of Chicago, chairman of the committee that drafted the document, said "certain ambiguities" were purposely included in the pastoral. "We do not give a moral analysis of every possible case," he said.

The implication of the restriction on bombing population centers is a condemnation of the U.S. use of atomic bombs dropped on Hiroshima and Nagasaki in 1945.

Those events, which some military strategists credit with bringing a quicker end to World War II, are not specifically mentioned in the pastoral other than in an observation that the United States is the only nation to have used nuclear weapons in combat.

A major source of criticism of the draft is its 110-page length, Gumbleton noted. This is particularly a problem in light of the bishops' avowed intention to use the statement to influence public policy.

"We seek to encourage a public attitude which sets stringent limits on the kind of actions our government will take on nuclear policy in our name," the document says. "We believe religious leaders have a task in concert with public officials, analysts, private organizations and the media to set the limits beyond which our military policy should not move in word or action."