Found this cool animated GIF last night. It’s from the April 1980 issue of Skateboarder Magazne — Matt Barden doing an M80. I’m seeing a few places that he is the inventor of the trick.
For me, they way he does them would be an M80 to fakie, but that’s because I do my kickflips with the wrong foot. Oh well. Gonna pay some attention to learning this.