It's too bad about Spirit. Their families sued Led Zep a few years ago for stealing 4 bars of music for Stairway to Heaven. Really? Copyright trolls, now, after all this time? It was stupid bad.
I'm sure Zeppelin borrowed from them unintentionally but a band like this has no business making an argument like "My Sweet Lord" sounds too much like "He's So Fine." 😁 "Randy California" always sounded like Hendrix.
So what. Who cares? You have to appreciate California's post-Hendrix-peer guitar playing. This is later, stripped down. But Spirit were around a long while and they were good-to-great at times.
This looks like a good document, I'm only partway through. Good post-Hendrix jams. Glad it's been preserved.
And they have a song called "Mr. Skin" that sounds really great! Good stuph. Respect.