Not sure if this has been mentioned yet, but I find it an interesting bit of trivia... Shaw and Garnett also play together on Andrew Hill's LIFT EVERY VOICE, recorded more than a year earlier (when they were both with Blakey, I presume).
I too like the Steeplechase date.
There appears to be a solo recital on Progressive (MEMORIES), but I've never heard it. Progressive have reissued a couple of LPs (A PEARL FOR ERROL and A PRAYER FOR LILIANE) on a single CD.
Edit: MEMORIES can be auditioned via Spotify. https://open.spotify.com/album/1OdFnWqBzjISimE3JyUJXs
Doesn't Donald Byrd play pocket trumpet on FUEGO? Recording date: October 4, 1959.
The "toy instruments" were part of the whole Ornette Coleman Quartet package at the time. I can imagine those visuals might have made the music sound even more disorienting / alienating to someone like Mingus whose avant-garde roots were more Third Stream.
Spotted on the YouTubes. Some fun anecdotes here. There's a follow-up video in which the host shows off a few items from the collection (since pushed to Ebay). He's also promised to do more show and tell in future videos.