In the spirit of glasnost, it would have seemed fitting for Mikhail Gorbachev to be the first guest in the remodeled Blair-Lee House, the nation's once and future guest quarters.

He could have been the first to whirl in the Jacuzzi in the Head of State Suite, to dream while he slept on the all-new mattresses and box springs given by Simmons Co., to stroll in the Arthur and Janet Ross Garden. But he would have had to wait until early spring -- instead of November -- to visit the Reagans, and the world might have fallen apart by then.

"General Services Administrator Terence Golden has promised me we'll have the construction work finished and the house turned over to us by November 1," says U.S. Chief of Protocol Selwa Roosevelt.

But the interior decoration is expected to take another four or five months after that, says Clement Conger, Blair House and State Department diplomatic reception rooms curator.

The guest house is actually four interconnected houses of 105 rooms -- the Blair and Lee houses in the 1600 block of Pennsylvania Avenue NW, and the houses adjoining at 700 and 704 Jackson Place.

The old houses are being restored to their early-to-mid-19th-century fac ades. Roosevelt says the Fine Arts Commission insisted that Lee House, (next to the Renwick) be returned to its original red brick. The link, or hyphen, on the east, connecting Blair House and 700 Jackson Place, was rebuilt of the same red brick. The finished coat of stucco on Blair House will be painted white.

A new two-story wing, 65 by 35 feet, is as large as any of the four houses. It begins at the hyphen between Blair House and Jackson Place, to be used for powder rooms and coatrooms. And it goes straight back, behind the Jackson Place houses. Upstairs is a Head of State Suite. The ground floor is the Garden Room, 40 feet square with 16-foot-high ceilings, to which former ambassadors Walter and Leonore Annenberg (herself the former chief of protocol) of Wynnewood, Pa., and his sister, Janet Annenberg Hooker of New York, contributed $200,000.

"The new wing is built of an Ohio sandstone much like that from Aquia Creek, George Washington's quarry, used for the White House and the Capitol," said John Waite, a partner with Mendel, Mesick, Cohen, Waite, the Albany, N.Y., renovation architects. "And we found a quarry in Ohio that had the right brownstone for the stoop of 704 Jackson Place."

The front gardens will be unified by plantings designed by Richard Webel, of Webel and Innocenti of Long Island, and paid for by Alyne Massey of Nashville. Fleur Cowles gave $50,000 for a small back patio.

Decorator Mario Buatta says the Garden Room will serve as the setting for "lunches, dinners, dining -- parties of more than 16. It'll have trees and plants, tables for cards, big upholstery pieces."

"Now we won't have to move the furniture all the time to have large parties," says Roosevelt. "We can put seven tables in there, and maybe have 200 people."

"The new wing is a beautiful structure," says Kenneth Grunley, vice president of Grunley-Walsh, the construction company doing the restoration. He listed its royal elegancies: "plaster cornices, crotched mahogany doors, marble baths with bidets and Jacuzzis." The four old houses, he implied, are of plainer, plebeian stock -- "built for private people, not for kings and queens."

Congress appropriated $8.6 million for the entire remodeling and the new addition. To that, the Blair House Restoration Fund, presided over by Anne Armstrong, has added $4.6 million.

Says Roosevelt: "We've gone beyond our goal, but we're hoping for more to endow the house." Among the recent donations: Tiffany & Co. gave Blair House 150 (one for each year of the company's history) settings of silver called English King, a grand old traditional pattern that incorporates a shell design, says Fernanda Gilligan, Tiffany vice president.

For the Head of State Suite (sitting room, two bedrooms and bath), "we have the Josephine Mercy Heathcote Foundation of 18th-century English antiques," says Buatta. "About 70 to 80 pieces. They're worth well over a million."

In the Lee drawing room, the 18th-century Chinese wallpaper given by C. Douglas Dillon 25 years ago has been restored (at his expense), and the color scheme is matched to it.

The central Blair House drawing and dining rooms, and the historic second-floor library as well as the five suites and numerous bedrooms, are the province of decorator Mark Hampton.

"We've aimed at keeping it a private American house with a concern for the 19th century," he says. "We've kept all the historic woodwork and plaster work, and the great 19th-century Carrara marble fireplace, which came from the White House. We've used faded rose, off-white, off-green and melon colors." Hampton also designed the press room in the Jackson Place house, to serve 150. The house "is full of security rooms, because the foreign guests bring their own."

Hobart Co. has equipped the kitchen with big appliances; Bloomingdale's has outfitted it.

And when it's all finished, the house will be immortalized in a book to be published by Thomasson and Grant in Charlottesville, Va.