I had previously thought that King 5274 was the latest 78 on that label. But here is King 5289 from November 1959, “Look at Little Sister” by Hank Ballard and the Midnighters. The “B” side is “I Said I Wouldn’t Beg You.” “Little Sister” is pure rock and roll featuring hilarious lyrics like:
What about the neighbors? What they gonna say? Stop! Little sister’s getting carried away!
American 78s - The Last Year 
It’s been on You Tube for apx. 10 years.. After reading your update, I found it..
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Yep. That’s where I screen shot it.
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