WILL THEY SOAR, OR BE SORE?

Two middle-aged retirees playing a game of half-court one-on-one doesn't exactly sound like an event worthy of pay-per-view television. But when the two guys are basketball legends Julius (Dr. J) Erving and Kareem Abdul-Jabbar, it's a whole new jar of jam. Their ''Clash of the Legends'' hoopfest appears live from Atlantic City, N.J., Feb. 28 at 9 p.m. The scoring superstars are keeping mum about any plannes in-flight tactics. ''I'm not at liberty to totally divulge my strategy,'' says Erving, whose business partner, Dave Wooley, came up with the idea for this venture. The Abdul-Jabbar line: ''I have to do it all.'' Both perennial All-Stars averaged 24 points a game during their NBA careers; Abdul-Jabbar was on six