Bob Lewis scored seven points in overtime and led the North Carolina Tar Heels to a 78-70 victory over Princeton last night in the Semifinals of the NCAA Eastern Regional Basketball Tournament.

North Carolina, the nation's No. 4 team, blew an eight point lead in the final seven minutes of regulation time as its attempt to stall and run out the clock backfired.

Princeton outscored North Carolina from the floor 30-23, but they lost at the foul line as they were outshot 32-10.

In the other semifinal match last night, Boston College overcame a nine point deficit in the last six minutes and defeated St. John's, 63-62.

The winning Eagles, who sank 23 of 25 free throws in the second half, went ahead, 61-60, with 55 seconds remaining on two foul shots by Willie Wolters. Billy Evans then intercepted a pass, was fouled, and sank both free throws to make it 63-60.

Steve Adelman of Boston College scored 17 points, 13 in the second half.

North Carolina and B.C. will play for the regional title tonight.