NBC Scores Big Ratings With Super Bowl XXVII : Television: Dallas’ romp of Buffalo is estimated to have drawn at least 120 million viewers and the highest overnight ratings since 1987.

Despite its customary rout, Super Bowl XXVII Sunday earned NBC the game’s highest overnight ratings since 1987 and figures to finish as at least the third most-watched ever when final national figures are released today.

The network’s telecast of the Dallas Cowboys’ 52-17 victory over the Buffalo Bills at the Rose Bowl averaged a 43.9 rating and 65% share of the audience in the 28 markets for which the A. C. Nielsen Co. had ratings data Monday. An NBC Research estimate expects the average audience to be in excess of 120 million viewers.

“It’s a very encouraging number,” said an ABC executive who asked not to be identified. “It’s great that the NFL still has great drawing power.”

Those were the best overnight figures since the New York Giants’ 39-20 victory over the Denver Broncos drew a 47.9 on CBS in 1987. The Washington Redskins’ 37-24 victory over Buffalo in last year’s game on CBS had a 40.4 overnight rating and drew a 60% share of the audience. The national ratings were 0.1 and 1.1 points lower, respectively, than the overnight figures of the past two years.

If the overnight ratings--which represent half of the nation--hold, it would be the 13th-highest rated Super Bowl. The 1982 game between the San Francisco 49ers and Cincinnati Bengals is the leader with a 49.1. (Viewership can rise while ratings decline at the same time because of the increased number of potential viewers and television sets. Ratings for all types of television programs have declined in recent years as the increased choices provided by cable, the Fox network, independent stations and videocassette recorders have siphoned away viewers.)

The audience of more than 120 million would edge last year’s game (about 119,680,000) but fall behind 1987’s (122,640,000) and the approximately 127 million who watched the Chicago Bears’ 46-10 1986 victory over the New England Patriots on NBC.

NBC had long assured itself of a profit on the Super Bowl, after selling out all 56 30-second commercial spots at $850,000 a piece early last month.

The presence of Michael Jackson and the Dallas Cowboys are among the factors boosting the ratings. The halftime show, which featured the self-anointed King of Pop lip-synching, had a 44.4 rating with an estimated viewership of 125 million. Last year’s halftime show, which had to face counter-programming from a live episode of “In Living Color” on Fox, had a 32.8 national rating.

The Cowboys again showed their national popularity. Dubbed in the 1970s as “America’s Team” after selling more merchandise than any other NFL franchise, Dallas’ five previous Super Bowl appearances brought in four of the five largest audience shares.

This time, Texas was responsible for the three highest-rated markets, Dallas-Fort Worth (58), San Antonio (53.3) and Houston (50.8). (Buffalo is not one of the 28 markets in Nielsen’s overnight survey.) The Los Angeles market was tied for eighth with Denver, with a 45.9. With each rating point in Los Angeles being equivalent to 49,657 households, it means that about 2,279,000 were tuned in.

St. Louis, which hasn’t had an NFL team since its Cardinals moved to Phoenix following the 1987 season, was the lowest of the 28 markets with a 33.4.

Viewership dropped a bit in the fourth quarter as Dallas scored three touchdowns to complete its romp. From 6-6:30 p.m. (PST) the rating was 43.6 and the final 15 minutes of the telecast had a 42.3. By comparison, the game drew a 44.1 from 4-4:30 p.m. (parts of the first and second quarters), a 45.2 from 4:30-5 p.m. and 44.2 from 5:30-6 p.m. during the third quarter.

The Super Bowl also provided beleaguered NBC with some good news for its entertainment programs during a season in which the network has been mired in third place and had to cope with several debacles and missteps.

The post-game premiere of the much-promoted drama series “Homicide: Life on the Street” had a 19.4 rating, 31 share and approximately 43 million viewers, surpassing the network’s expectations, a spokeswoman said.