The phrase "a large margin over" is correct and usable in written English.
It can be used when comparing quantities, scores, or results to indicate a significant difference in favor of one side.
Example: "The team won the match with a large margin over their opponents, securing their place in the finals."
Alternatives: "a significant lead over" or "a wide gap over".
Obama carried Minnesota by a large margin over rival Hillary Rodham Clinton last month.
The Americans lead the overall standings -- called the Global Cup -- by a large margin over second-place Russia, third-place France and fourth-place China.
Jealous won strong pluralities in the Baltimore area and did well enough in the populous Washington suburbs to win by a large margin over Baker and the others.
Seeking to explain the defeat, even before Mr. Lazio had actually conceded, they noted that Democrats hold a two-million-vote edge in New York, and that Vice President Al Gore, the Democratic candidate for president, seemed to be winning by a large margin over George W. Bush in New York, according to the survey of voters leaving the polls.
In a new national survey of Hispanics conducted by CNN/ORC, Latinos said that Mr. Obama would do better on a number of issues by a large margin over Mr. Romney, including the economy (40 points), immigration (54 points) and education (57 points).
Gnassingbé, again standing as the candidate of the long-time ruling party, the RPT, was said to be the winner by a large margin over his closest opponent, but the main opposition group, Union of Forces of Change (Union des Forces du Changement; UFC), disputed the outcome.
Indeed, the re-run of May's neck-and-neck presidential contest gave Van der Bellen a larger margin over his rival than seven months ago.
Throughput follows a similar pattern, with SACS obtaining a small margin over LFU, and a larger margin over LRU.
The Americans lead the overall standings — dubbed the Global Cup — by a large margin this year over second-place Russia, third-place France and fourth-place China.
Australia launched itself into the tournament proper by beating Pakistan by 34 runs, a large margin in a 20-over-a-side match.
By a large margin, the public over all said more regulation of offshore drilling to protect the environment was needed, but respondents were also more likely to attribute the BP accident to a failure of the federal government to enforce existing rules than to a lack of adequate regulation.
