The late Frank Zappa’s “vaultmeister” has unearthed 23 previously unreleased and rare recordings that Zappa may have been considering for a sequel to his beloved jazz-rock masterpiece, 1969’s Hot Rats.

The apocrypha, which totals three-and-a-half hours of music, will finally come out on June 30 via a three-disc set titled Funky Nothingness.

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Zappa’s estate is previewing the set with Zappa’s interpretations of two songs from 1954 by Hank Ballard and the Midnighters, “Work With Me Annie/Annie Had a Baby,” with violinist Don “Sugarcane” Harris singing lead:

The recordings, cut in February and March 1970, find Zappa playing with a lineup similar to the one on Hot Rats: multi-instrumentalist Ian Underwood, violinist and vocalist “Sugarcane” Harris, Wrecking Crew bassist Max Bennett, and drummer Aynsley Dunbar. The music, which mostly is instrumental, includes Zappa originals, cover songs, and improvisational jams that the estate says lean on R&B, blues, and jazz influences.

The compilation includes a couple of previously released tracks (“Sharleena” came out on 1996’s The Lost Episodes) but the music is recontextualized on Funky Nothingness.

The release, co-produced by Travers and Zappa’s son, Ahmet, will be available in a variety of formats, including a three-CD version featuring the 11-track album, featuring Zappa’s original mixes of the songs, compiled along with two bonus discs of outtakes. It includes a booklet with photos from the session. It will also be available to stream and download in both standard and high-resolution formats. There will also be double-LP pressings in a variety of colors.

“Funky Nothingness, as an album, is special in that it features at least three written compositions, three cover versions, and multiple instrumental jam-oriented segments, all previously unreleased,” vaultmeister Joe Travers said in a statement. “It’s very rare to find that amount of music from one set of sessions that has gone unheard for such a long period of time.”

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Although many of the songs are instrumental, Zappa sings a 12-and-a-half–minute interpretation of Lightnin’ Slim’s “I’m a Rollin’ Stone” (Zappa later used the music from the track for “Stink-Foot”), and Sugarcane sings “Love Will Make Your Mind Go Wild.” Some of the instrumentals, including “Khaki Sack” and “Twinkle…