Upon learning that the ancestor of the modern guitar was tuned similarly to the ukulele, he reacquainted himself with the instrument, commissioning an Italian luthier to make a classical ukulele for him. With it, he revived a guitar-playing technique from the Baroque era: succeeding notes are played on different strings, allowing the previous note to continue ringing. Known as campanella style, which means 'little bells' in Latin. His influential book The Classical Ukulele is part of Jim Beloff’s Jumpin’ Jim’s Ukulele Masters series.

King recorded two records and wrote several books of ukulele arrangements. He did extensive research into the history of classical guitar and the ukulele, writing numerous essays. He wrote an encyclopedia of Hawaiian luthiers. He was working on a history of the ukulele with Jim Tranquada at the time of his death which was published in 2012, The Ukulele: A History, published by the University of Hawaii Press.