No kit was ever made. It was published in Model Airplane News in 1970. I'd have to go look at the issue to remember the month. The published version was somewhat different from Don's original as he had made some minor changes before publication. This is the original Avenger, called the Avenger 35. The slightly updated version was just called the Avenger. A few years later, Don designed the Avenger 76. Same wing/flaps and stab/elevator but a different fuse with a trike gear. I may yet build one for Super 70s.
Don was a disciple of Bob Gialdini and the Avenger was based, loosely, on Bob's Stingray.
Let's see, the other thing is, Mark, at the time of that picture, was a custom auto painter and a very talented guy (he's still a talented guy and a flying buddy). The finish on his Avenger was spectacular. Probably why he won the concours d'elegance award at VSC. Only drawback was, it took a lot of layers of paint. That, and the mods he made are why my original Avenger weighted 48oz (2 ounces more than Don's original) and Mark's weighed, well, a lot more.