A near-sellout crowd of more than 50,000 is expected Sunday at RFK Stadium for the North American Soccer League's Soccer Bowl 80 between the Cosmos and the Fort Lauderdale Strikers.

As of yesterday morning, ticket sales already had reached 42,000 -- exceeding the 40,000 guaranteed by a group of Washington-area business leaders as a condition for bringing the Soccer Bowl to Washington. In New York, a spokesman for the Cosmos reported brisk ticket sales yesterday, with about 5,000 Cosmos fans preparing to come to the match on chartered buses.

From Fort Lauderdale, the Strikers reported about 700 fans making the trip to Washington, including about 150 on a special airline package.

Tickets priced at $10 should be available at the stadium the day of the game, the NASL reported. Kickoff is at 12:30 p.m. The game will be televised nationally by ABC (WJLA-TV-7 in Washington). A spokesman for ABC Sports said the network was hoping to draw an audience of 11 million, which would be a record for a soccer match televised in the United States.

The game was intentionally scheduled early so as not to conflict with the Washington Redskins-Oakland Raiders football game at 4 p.m.

The Greater Washington Sports Authority, a coalition of government and business leaders promoting the game, is encouraging fans to ride Metro to the stadium. Extra trains have been scheduled to handle the anticipated crowds.

For those driving, parking is available in the stadium lots at $2 a car.

Among the notables expected to attend the game are former Secretary of State Henry Kissinger, chairman of the board of the NASL and a self-described "ex-goalkeeper of no note;" George Bush, Republican vice-presidential candidate; Hermann Neuberger, chairman of the World Cup organizing committee for the 1974 and 1978 tournaments, and for the 1982 tourney, to be held in Spain; Hans Bangerter, secretary general of the Union of European Football Associations, and William Meuleman, president of the Dutch Federal Football Association.

Meeting in Washington yesterday, owners of the NASL franchises gave formal approval to two franchise shifts from the United States to Canada.

Approved for transfer from Philadelphia to Montreal was the Fury franchise, which has been purchased by the Moison Brewery. Going from Memphis to Calgary are the Rogues, purchased by Canadian businessman Nelson Skalbania. Responding to owner concerns that there have been too many franchise changes in the NASL, Skalbania has complied with owner requests that he promise to keep the team in Calgary for at least three years. r

The site for next year's Soccer Bowl will be chosen at the NASL's Oct. 20-22 meeting in Toronto. Among the contenders are Detroit, Vancouver and Toronto. Giants Stadium in East Rutherford, N.J., also is considered a possibility, but it is said to be a less likely site because the last two Soccer Bowls, were held there and the Cosmos are not anxious to play host to the event again so soon.