Complex sentence: Rundgren contacted Moogy Klingman, who appears on several tracks, and would later co-found Utopia with him, instructing him to find the best session players possible for the recording.
Split into simpler sentences: Rundgren contacted Moogy Klingman, who would appear on several tracks and later co-found Utopia with Rundgren. Rundgren instructed Klingman to find the best session players possible for the recording.