Across the street from one of the most heinous architectural crimes of the 20th century looms a chance for a storybook ending.

The crime was the 1963 demolition of Pennsylvania Station, a soaring temple of rail transport that novelist Thomas Wolfe lovingly described as "murmurous with the immense and distant sound of time." The happy ending can be found just across Eighth Avenue. It is behind the Corinthian columns of the cavernous General Post Office.

That landmark building happens to have been designed by the same architecture firm that designed Pennsylvania Station. What is more, the two-block-square post office almost exactly matches the dimensions of the old station. It has skylights in places where the old station had skylights. Built when trains carried most of the mail, the post office sits above Amtrak rail tracks and passenger platforms. Politicians and architects agree that its conversion to a glorious train station would be as easy as pie.

"It was an act of vandalism to destroy Pennsylvania Station. It is a remarkable serendipity that we should have a second chance to recreate it," said Sen. Daniel Patrick Moynihan (D-N.Y.), who for more than four years has angled for federal funds, twisted President Clinton's arm and enlisted former staff members to infiltrate and advance the cause of a reborn station.

The senior senator from New York is on the brink of getting his way. A 35-year season of lament over the flattening of Pennsylvania Station, along with endless carping over the cramped replacement station that squats beneath Madison Square Garden, is drawing to a close. Federal, state and city officials are lining up behind a public-private $315 million plan to convert part of the post office into a monumental reincarnation of the late, great train station that was based on the Baths of the Emperor Caracalla in Rome. Work may start this summer.

A new Pennsylvania Station would be the jewel in the crown of a burgeoning movement that has brought back dozens of run-down train stations from Washington to Los Angeles, resurrecting them as imposing hubs of transport, shopping and culture. It also would be the capstone to a revival of New York City that has seen crime plummet, real estate values soar and tourists swarm.

Outrage among New Yorkers over the destruction of Pennsylvania Station helped save the city's other magnificent train station. The Landmark Preservation Commission, created in 1965 in response to the razing of Penn Station, quickly bestowed landmark status on Grand Central Terminal.

That status, upheld by the U.S. Supreme Court in 1978, has protected Grand Central from an assortment of unsightly development schemes. One would have put a 54-story office tower over the station. Another would have sliced up its vast, vaulted main waiting room into four stories and put bowling alleys on the third level.

Half a million travelers pass daily through the gloomy crypt that is now Penn Station, including most of those who arrive from Washington. With its dim lighting, low ceilings and worn flooring, it is still by far the country's busiest rail center. A new train station would mean that Amtrak passengers no longer would be compelled to scurry up into the city like rats.

"It may be too logical to happen in New York," frets Alexandros Washburn, president of the Pennsylvania Station Redevelopment Corp., a New York state agency akin to the one that revived Washington's Union Station a decade ago. Washburn is an architect who until two years ago worked in Moynihan's Senate office and whose permanent marching orders from the senator remain: "You get Pennsylvania Station built."

There is some reason to fret. The U.S. Postal Service is not keen on walking away from a building it regards as the nation's flagship post office. The granite colossus on Eighth Avenue bears its unofficial motto about how "Neither snow, nor rain, nor heat, nor gloom of night stays these couriers from the swift completion of their appointed rounds."

Postal Service executives say they want to be cooperative and civic-minded, but not at the cost of slowing the mail.

"You have people whose day-to-day responsibility is moving the mail. They are not comfortable moving in an arena that involves redevelopment of the building. It gets political. You don't want to layer this on to people who must make on-time deliveries," said Rudy Umscheid, vice president for facilities for the Postal Service in Washington.

Federal officials last month announced an agreement in principle between the Postal Service and developers that would surrender space in the post office, officially known as the James A. Farley Building, for a new Pennsylvania Station. But exactly how much space and when it will be handed over are still hotly disputed.

The New York Municipal Arts Society, a well-heeled group that advocates preservation of the city's landmark buildings, is demanding nothing less than the entire building, leaving the Postal Service with only its public lobby along Eighth Avenue. The rest would be taken for the train station and an ambitious plan for retail, exhibition and concert space.

"If you planned this all at once, rather than piecemeal over time, it would be more attractive and less costly," said Philip K. Howard, chairman of the Municipal Arts Society.

A glossy Municipal Arts Society "master plan" brochure derides the Postal Service for managing its building as a "dilapidated warehouse" that needs to be rescued from the noise and filth of mail trucks in order to "spur the renaissance of a now-moribund commercial district on the lower West Side. . . . All that is needed is one great integrated plan."

Preservationists have a point. As the Postal Service concedes, "there are vacant spaces" in the 1.3-million-square-foot building. Much of what isn't vacant is used for plebeian purposes such as storing mailbags and hammering dents out of mailboxes.

The 24-hour-a-day pounding of huge mail trucks going around and into a loading dock on the first floor of the building has hastened the deterioration of the Classical Revival stone ornaments that line the perimeter of the roof. A permanent scaffolding on Ninth Avenue keeps the intermittent showers of stone from bonking passersby on the head.

There are 2,400 postal employees, however, who still work in the building, down from 6,000 before most mail-sorting was moved elsewhere. About 11 million pieces of mail flow through the building each week, going out to a quarter-million people.

"We understand the importance to New York of this wonderful, monumental old building, but we also want to provide first-class mail service. If mail service went in the tank, we would be severely criticized and vulnerable," said Umscheid, the facilities boss for the Postal Service.

The clash between those who would beautify New York City and those who would deliver the mail -- while hanging on to spacious digs -- produced, until last month, a nasty case of bureaucratic paralysis.

It was reminiscent of the corrosive infighting over Washington's Union Station in the 1970s between the departments of Transportation and Interior. As the roof leaked, rats ran free and toadstools grew in the foul-smelling basement of that monumental train station, bureaucrats elbowed each other for years, with Interior demanding dominance for a visitor center and Transportation demanding the same for the sake of trains.

It was Moynihan's office, in the person of staff member Robert A. Peck, that helped break the logjam in Washington and smooth the redevelopment of Union Station. Peck is now the federal commissioner of buildings, but he remains mindful of his former boss's passion to get Penn Station built. So he is trying to perform a similar Solomonic function in easing the Postal Service out of most of its building in Manhattan.

"The breakthrough in New York came when they stopped lobbing grenades back and forth about how many square feet the train station would occupy. Both sides are now recognizing that it is a whole lot nicer to cooperate than to threaten to cut each other's utilities off," said Peck, who was asked by President Clinton, at Moynihan's urging, to mediate between the Postal Service and the train station boosters.

Peck said both sides have agreed to phased redevelopment of the post office building. The agreement, Peck said, "gives the train station about as much space as anyone has ever suggested was necessary for a train station." But it postpones decisions about when the Postal Service should clear out for development of retail, exhibition and theater space.

The compromise, which remains a work in progress, does not thrill either the Postal Service or New Yorkers who hunger for the immediate development of a "vibrant gateway" at Pennsylvania Station. But Moynihan said he is pleased.

The senator's aides said he expects that the Postal Service, over time, will see the civic and financial wisdom of moving elsewhere. The Postal Service could earn $100 million or more by selling "air rights" to its building. In this vertical city, such rights are a kind of financial commodity that can be sold to nearby property owners to erect a skyscraper.

In the meantime, there are rumblings that the new train station could be named after Moynihan. On this, the senator declines comment. CAPTION: Rebirth of a Landmark A plan is gaining steam to reproduce Manhattan's Penn Station in its original glory. "It is a remarkable serendipity that we should have a second chance to recreate it," said Sen. Daniel Patrick Moynihan (D-N.Y.), who is championing the effort. The past: The original marble and granite structure, with its magnificent arcade, waiting room and concourse, was built in 1910. The station was demolished in 1963 because its owner, the Pennsylvania Railroad, was losing $37 million a year keeping it open. The present: The station, which sits below Madison Square Garden, is the country's busiest, with 500,000 passengers a day. It is so crowded that it takes 10 minutes to clear the passengers from each train. The future: The new station would be erected inside what is now the city's main post office, a granite building designed by the same architects who designed the original station. It matches the original's structure exactly, and the train tracks run below. CAPTION: New York City's General Post Office is scheduled to be transformed into a reincarnation of Pennsylvania Station, its architectural twin across the street. The original Penn Station was demolished in 1963.