Musicians

Copyrights for songs written after '78 last 70 years.
Before that, they lasted for 28 years, but could be renewed for another 67. A total of 95 years.
If you find a song written in the early 70s, and nobody applied for renewal, there is no copyright upon which to infringe.
Seems it might be easier for someone here to come up with blues changes and an "original" melody.
Chord progressions can't be copyrighted, so any blues changes are unencumbered for use.
And, evoking an existing melody with totally different words probably couldn't be pursued because you're not monetizing.
Besides, copyrights can be satisfied by paying a usage fee, which is pennies & nickels since there's no % of sales to discuss.
Finally, YouTube & SoundCloud (and likely others) run a check when posting to assure to infringement.
The stuff I have online is 100% covers, and everything I ever tried to post passed the screening
You might be overthinking this.