The House Assassinations Committee got a new chairman yesterday after the resignation of Rep. Henry B. Gonzalez (D-Tex.) was accepted on the House floor by a vote of 296 to 100.

Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) named Rep. Louise Stokes (D-Ohio) to preside over the uncertain inquiry, which will go out of business March 31 unless the House votes to continue it.

Stokes took heart inthe top-heavy vote accept Gonzalez' resignation, which he said he felt was "in some ways a barometer of the feelings of the House" about the investigation, but others saw no connection. House Majority Leader Jim Wright (D-Tex.) emphasized in a floor speech that Gonzalez no longer wanted any part of the committee and hoped the House would simply accept his resignation without a fuss.

"The fight is still uphill," Wright told reporters later of the committee's struggle to stay alive. "The chances for survival are somewhat unlikely."

Others privately said they saw Stokes' appointment as a sign of hope only for the investigation of the murder of the Rev. Martin Luther King Jr. The Cleveland Democrat is one of the four members of the Congressional Black Caucus appointed to the 12-member committee last September as a result of the caucus' special interest in the King assassination.

Stokes however, said he thinks it "absolutely essential that the original intent of the committee be carried forth" to investigate the assassinations of both President Kennedy and of King. He said in a short press conference that the committee may release some sort of preliminary report on the evidence gathered thus far in hopes of generating sufficient support.

Gonzalez lasted as chairman little more than a month. Appointed Feb. 2, he ran into resistance from chief counsel Richard A. Sprague, and was overruled by all 11 other members of the committee when he tried to fire Sprague.

O'Neill had initially said he would not submit Gonzalez' resignation to the House until he first had a chance to try to dissuade him, but O'Neill said yesterday that all his efforts to contact the ailing chairman had been futile. Gonzalez has been recovering from the flu in his San Antonio home.

Several committee members had hoped the speaker would appoint Rep. Richardson Preyer (D-N.C.), the ranking Democrat, as the new chairman, but O'Neill said he want Preyer as chairman of the about-to-be-created House ethics committee.

Preyer, for his part, had urged appointment of someone not now on the committee, but O'Neill said he decided on Stokes, the next-ranking Democrat, because "I just feel those on the committee are more knowledgeable" about the inquiry.

Yesterday's roll-call vote was demanded by Rep. Robert E. Bauman (R-Md.), an early critic of the investigation, who said the House should first have an opportunity to discuss the charges of mismanagement and insubordination which Gonzalec had leveled against Sprague.

The debate, however, lasted only a few minures, and consisted largely of attacks on the press by members of the Assassinations Committee. Rep. Stuart B. McKinney (R-Conn.) charged that the media had created the "erroneous" impression that the committee was in disarray when everyone - except Gonzalec - was "very firmly together."