The good and bad news about the big new Navy that President Reagan wants to build can be found here at the nation's largest shipyard.

Newport News Shipbuilding and Dry Dock Co. is booming because of billions of dollars in orders for nuclear carriers and submarines the Navy insists it needs to regain "maritime superiority" over the Soviet Union.

But it remains uncertain whether bust may soon follow boom at Newport News and other American yards, just as in the past when Washington had second thoughts and decided it could not afford to carry out an ambitious shipbuilding plan after all.

Navy Secretary John F. Lehman Jr. insists it will be different this time. The Navy will have 600 warships by the end of this decade, he vows, including 15 aircraft carriers and their escorting warships.

Rep. Joseph P. Addabbo (D-N.Y.), chairman of the House Appropriations subcommittee on defense, has different ideas. He will soon begin a campaign to strike the two Nimitz carriers from the Pentagon's fiscal 1983 budget.

If Lehman and his allies win, Newport News, the only yard that can build nuclear aircraft carriers, will get most of the $6.8 billion earmarked for the two giants.

But if Addabbo prevails, Newport News Shipbuilding executives figure 5,000 jobs will sink with each carrier deleted from the defense money bill. They stress, however, that the yard will scramble for other work to avoid layoffs in the work force of 25,000, about 70 percent blue-collar jobs.

The big question, then, hanging over the Navy budget for the rest of this decade is whether its shipbuilding program will be adjudged too vast and costly in light of the huge federal budget deficits piling up and the money needed for such strategic weaponry as the Navy's own Trident missile submarine, the Army's antiballistic-missile, and the Air Force's bombers and MX missiles.

Lehman, pointing to the feverish pace of shipbuilding here as Exhibit A, contended in an interview with The Washington Post that it will be as difficult for the naysayers to stop the Navy from getting its 600 warships by 1990 as it is to stop a supertanker going full speed ahead.

The scene inside the gates of this 475-acre shipyard on the James River shows that Navy shipbuilding is indeed full speed ahead -- at least for now. The Newport News yard looks like a walled city getting ready for war.

Foremen in white hardhats have so many armorers to supervise that they pedal balloon tire bicycles from one work shed to the other along the two miles of James River waterfront. Inside the sheds, men and women shape steel, braze joints in miles of pipe, and weld together rings of steel that form the cigar-shaped hulls of modern nuclear-powered submarines.

Outside, standing on fill that replaced river water, a rigger blows his whistle to warn workers away from the 22-story crane hustling steel plates to Shipway 12, the drydock where the next Nimitz class nuclear aircraft carrier, the Theodore Roosevelt, is rising high above the flatness of the yard.

The air in an adjacent area is acrid from all the welding on nuclear attack submarines, which cost about $800 million each, under construction. Newport News has orders in hand for 10 and expect to get more.

Young men who know how hard it is to land nondefense jobs outside the yard marvel at the bustle at Newport News Shipbuilding. "They're still hiring," said Michael Wyke, 31, of Virginia Beach, an $8.22 an hour welder. "It looks real good." He said he takes home $300, including some overtime pay, in a good week.

James Gallagher, 21, of Laurel, Del., provided a contrast as he stood inside Schugam's pawn shop across the street from the yard. "Walked for 30 miles around here and couldn't even get a waitress job," he complained. He had an application to work at the shipyard sticking out of his back pocket as he talked.

Navy Secretary Lehman is as bullish about getting his 600 ships by 1990, including 15 aircraft carriers and escorting warships, as Wyke is about keeping his job. "The fact is that we are there on a 600-ship Navy, unless there is some radical slash in the program now," he said, adding that he doubted this would be done by this administration or this Congress.

"The magnitude of the budget increases compounding what we have been getting has shifted us into an area where I don't see why people keep debating the 600-ship Navy," Lehman said.

Reagan's original fiscal 1983 defense budget requested $88.6 billion for the Navy, a jump of $18.9 billion over the previous year. His plan calls for steady increases of 7 percent, after allowing for inflation, for the next five years.

Focusing on the imminent battle with Addabbo over the two nuclear carriers in the fiscal 1983 budget, Lehman said, "I believe we have the votes and solid support in the House to defeat Addabbo's attempt to take both carriers out."

He believes the challenge no longer is getting the 600 ships built and deployed in the 1980s but keeping them in fighting condition and then moving on to their successors.

But Lehman is being overly optimistic, said another Pentagon executive who agrees the nation needs a robust shipbuilding program. This executive predicted the Trident submarines and its new D5 missile would draw so much money away from shipbuilding that the 600-ship fleet will continue to be as out of reach to today's admirals as the Holy Grail was to the storybook knights.

Each Trident submarine costs $1.5 billion, not counting the 24 missiles that go inside each one. Each current Trident missile costs more than $1 million. The new ones will cost still more.

The Congressional Budget Office, after analyzing the Navy's program for reaching a 600-ship fleet, concluded in a report issued in March that Reagan's blueprint calling for spending $80 billion to buy 133 ships over the next five years will not reach its goal. The report noted that, "as has been the case with so many previous plans," the Reagan blueprint "has most of its ships programmed in the later out-years."

Specifically, Reagan's five-year plan calls building 18 new ships in fiscal 1983, 21 in 1984, 24 in 1985, 32 in 1986 and 38 in 1987 to reach the total of 133. Reagan will finish his first term before the bulk of the shipbuilding program comes before Congress.

How much to spend on shipbuilding thus will continue to shape the Navy budget long after Lehman and Addabbo square off this year over the carriers. Whether Newport News Shipbuilding and other yards experience boom or bust in the future may well be up to another president and another Navy secretary.