Complex sentence: Beginning around the late 1940s, Henry's orchestra had over 300 arrangements, which included were some custom arrangements by his then pianist Bill Dixon, who scored recognizable vignettes of hummable works by Tchaikovsky, Rubinstein, Rachmaninoff, and Massenet.
Split into simpler sentences: Beginning around the late 1940s, Henry's orchestra had over 300 arrangements. Included were some custom arrangements by his then pianist Bill Dixon, who scored recognizable vignettes of hummable works by Tchaikovsky, Rubinstein, Rachmaninoff, and Massenet.