As Nassau Coliseum readies for the return of professional basketball with the NBA G-League Long Island Nets, the echoes of Dr. J’s thunderous house calls still resonate on the grounds.

Old Nassau Coliseum once was the stamping grounds for Julius Erving and the New York Nets, a team that had the makings of a dynasty if circumstances had been different.

Erving, who played on the Salvation Army basketball team in Hempstead before starring for Roose velt High School and the University of Massachusetts, came to his hometown American Basketball Association team from the Virginia Squires in 1973 and led the Nets to two championships in three seasons.

“He was everything you wanted to be in a basketball player,” said Alton Byrd, vice president of business operations for the LI Nets, who remembers watching Erving play at the Coliseum. “If God built a prototypical basketball player, it would have been Julius. Six-seven, big hands, run, jump. He was the epitome.’’

Erving spent only three seasons with the Nets, though. The professional basketball landscape was changing with the impending merger of the ABA with the more-established National Basketball Association. To be part of the merger, the Nets were required to pay $4.8 million to indemnify the Knicks for cutting into their territory, so Nets owner Roy Boe sold his star to the Philadelphia 76ers for $3 million. Shortly after Erving’s departure, the team was moved to New Jersey. Long Island hasn’t had a bona fide pro basketball team since.

“I BET HE CAN STILL DUNK”

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Erving, 67, and some of his former teammates may make cameo appearances at the Long Island Nets’ Coliseum games, the team said. “We would love to have not only Julius but all the guys who played for the Nets,’’ Byrd said.

But Dr. J is, was and always will be Mr. Basketball at the building in Uniondale. When fans of his generation close their eyes, they still can see him over the rim.

“I bet he can still dunk,’’ said former NBA executive Rod Thorn, 76, a Nets assistant coach during Erving’s tenure and the general manager for the Bulls when they drafted Michael Jordan. “Doc was more spectacular than Jordan,’’ he said.

“I think it’s a compliment just to be mentioned in the same sentence with certain people,” Erving said of Thorn’s Jordan comparison. But Erving said by phone from Atlanta, “The dunking days are behind me” after earlier noting that “I was 63 the last time I tried it.”

‘PEOPLE DIDN’T REALIZE

HOW GOOD THE ABA WAS’

Erving began dunking for the Nets in 1973-74, joining a team that went to the ABA Finals in 1971-72 with future Hall of Famer Rick Barry. The Nets were in their second season at the Coliseum — they moved there from 5,800-seat Island Garden in West Hempstead — when Erving, then 23, was obtained from Virginia.

Barry’s Nets opened the Coliseum against the Pittsburgh Condors on Feb. 11, 1972. “It seemed like a palace compared to the stuff we had played in,’’ said Barry, 73. “I had played in so many old arenas, to get into what was then a modern arena . . . I always have fond memories of that.’’

Erving recalled how ecstatic he was to play so close to home. “It was brand-new, state of the art,’’ he said. “It was such an enjoyable building.’’

Erving and other ABA stars lit up the 17,800-seat Coliseum. “There was no TV exposure,’’ former Nets coach Kevin Loughery, 77, said from Brookhaven, Georgia. “If we had cable at that time, it would have been a big different story. People didn’t realize how good the ABA was. After the merger, half of the All-Star team was from the ABA. Players like Moses Malone, Bobby Jones, David Thompson, Dan Issel.’’

Former St. John’s player Billy Schaeffer, 65, now the director of development for the school’s Peter J. Tobin College of Business, said the Coliseum was the ABA’s best facility.

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“Memphis was dark and old, San Diego was decrepit,’’ Schaef fer said. “Nassau Coliseum was really top-shelf.’’

Bill Melchionni, 72, who played for the Nets from 1969-76, said from Philadelphia, “Except for Madison Square Garden and The Forum in L.A., it was as good as any facility in the NBA.’’

Another St. John’s alum, Billy Paultz, said: “We had a great thing going. It was high-quality basketball, it was class basketball.’’

Paultz, 69, who now lives in Seabrook, Texas, watched the Coliseum being built while the team played at Island Garden, where, according to a 1972 Sports Illustrated story, promotions included giving away live baby turtles to young fans and releasing a dove in honor of former St. John’s player Sonny Dove.

Erving was known throughout the ABA. His coaches recalled a game against the Kentucky Colonels in which future baseball Hall of Famer Johnny Bench watched from a nearby seat as Dr. J dunked over 7-2 Artis Gilmore at Louisville’s Freedom Hall.

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“He fell off his chair,’’ Loughery said. Erving recalled that Loughery turned to him and said of Gilmore, “Don’t wake that guy up!’’

Said Thorn, “Every night Kevin and I would look at each other and say, ‘I can’t believe he did that.’ We had the best seat in the house for one of the greatest shows ever.’’

‘THEY HAD TO TRADE DOC’

But Erving alone could not hold the ABA together. The Nets and Erving had just defeated the Denver Nuggets for the 1975-76 ABA title when the merger brought the Nets, Nuggets, Indiana Pacers and San Antonio Spurs into the NBA. To join, however, the Nets were required to pay the Knicks $4.8 million as indemnification for moving into their territory. Some reports suggested that the Knicks rejected the Nets’ offer of Erving instead of the payment. Had that occurred, Erving said of the Knicks, “Their last title wouldn’t have been in ’73.”

Erving was sold to the 76ers to raise some of the required cash, forever changing the history of the Nets.

Sam Boe, 60, son of the late owner, said his father agonized “forever” over the Erving deal. “They wouldn’t do the merger unless the Nets came, and part of that was they had to trade Doc,’’ Boe said from Bedford in Westchester County.

The Nets went 22-60 in the 1976-77 season, their first in the NBA and their last at the Coliseum, where they averaged approximately 8,000 fans per game, according to the Association for Professional Basketball Research.

Boe moved the Nets to Piscataway, New Jersey, where they played at the Rutgers Athletic Center until the new Meadowlands Arena opened in 1981.

Erving won an NBA title with the 76ers in 1983. He never forgot his Long Island roots or the program he benefited from in his youth. Last year, he paid for a coach bus to take Hempstead’s Biddy Basketball team to a tournament, said Hempstead Village mayor Don Ryan, who coached Erving in his teen years.

What might the Nets have achieved playing in the Coliseum as an NBA franchise with Erving?

“We would have had a good team,’’ Thorn said, “and [Erving] would have been more spectacular.’’

With Neil Best