"Of course I know who Mr. Sabbatini is," said actor John Houseman in his dignified British high-tone. "He has dressed me. He has seen me naked."

And so, Mr. Houseman obliged the army of photographers on hand to record every little move last night at a reception at the opening of the exhibition of "Marco Polo: Costumes by Enrico Sabbatini" at the Textile Museum.

In addition to showing off the costumes created for "Marco Polo"--the $25- to $30-million mini-series to be aired on NBC next month--the fancy 6-to-8 p.m. cocktail party was part of The Big Push. With some of the movie's stars--Houseman, Burt Lancaster and Leonard Nimoy--at least 12 photographers and dozens of mostly off-duty reporters on hand, it was a corporation's dream of promotional heaven.

"Do you want me to set this shot up for you again?" yelled out Owen Comora, NBC's national publicity director, who seemed more like a tour director at the crammed museum.

"We'd rather have them looking happy to see each other than staring at us," yelled back a UPI photographer.

"I usually don't do these things," said Houseman. "They asked me to come."

What were the highlights of filming for the "Marco Polo" epic, in which the legendary actor plays patriarch of Venice?

"There are never any highlights," he said. "You just drag yourself from place to place."

Lancaster, who plays Pope Gregory X, was considerably more enthusiastic. "The thing that made the difference to me was that I had to wear these costumes from the underwear out, and it made the role more meaningful," he said, adding that his particular costume weighed 80 pounds. "There were substitute costumes . . . but Sabbatini made me wear the real thing."

A few minutes later, Sen. Strom Thurmond (R-S.C.) stopped in, and NBC PR man Comora took him by the hand and introduced him to all the NBC executives. There were many: chairman and chief executive officer Grant Tinker, president and chief operating officer Robert Mulholland, senior vice president Perry Lafferty, executive vice president Bud Rukeyser and scores of other producers, assistants and public relations staff members.

Procter & Gamble--the underwriter of the 10-hour movie--was also well represented.

"We expect this to be a good commercial venture for us that will encourage other corporations to do the same thing," said Owen Butler, chairman of Procter & Gamble. Procter & Gamble's financial input for production costs has been estimated at $10 million, which Butler says the company hopes to retrieve through prime-time advertising when the movie is aired.

The top draw for the party was originally expected to be Secretary of State Alexander M. Haig Jr., who canceled because of the Falkland Islands crisis. Defense Secretary Caspar Weinberger and Attorney General William French Smith had also accepted, but were not around. Italian Ambassador Rinaldo Petrignani and Chinese Ambassador Chai Zemin were the cohosts because, as everyone knows, Marco Polo traveled from Italy to China. The food at the reception included such delicacies as Tangerine Peel Chicken, Shanghai Shrimp, Kung Pao Beef and a rather large roast pig.

Petrignani hosted a private dinner following the reception for about 60, including the show's stars and NBC officials. And it was Ying Roucheng, China's best-known actor, who captured the crowd there. He arrived from China in the nick of time for dinner. Everyone cheered.