Thirty-one years and 26 miles later . . . the Los Angeles-originated vocal group the Four Preps, which had a No. 1 hit with "26 Miles (Santa Catalina)" in 1958, will perform on the island for the first time as part of the Avalon Ballroom's 60th anniversary celebration May 28. The current version of the Preps features two original members, plus former lead singers of the Lettermen and the Diamonds.