Some information about the Challenger (not about the Black Widow) is located here:
.https://www.flickr.com/photos/15794235@N06/10822272464/.
Says the copyrights were purchased by Coles Power Models.
The First Challenger V8, mid 1960s
Machinist Alfred Bachtold began making this engine, but needed help to complete it. He formed a loose partnership with pattern maker Clayton Thoms and designer Mr. Dettrick (first name unknown). Half-way through the project, the three men disagreed on how they would share profits from engine sales, so the partnership ended. Bachtold bought out the other two, and gave the prototype to Thoms.
The prototype is made of castings from the head down that remained part of the final design. The top end parts were machined by Bachtold from solid aluminum. The timing gear cover has the letters T/B cast into it, denoting Thoms and Bachtold.
In 1968, Lancer Engineering purchased the patterns and tooling from Bachtold. Lancer completed the patterns for the head, intake and exhaust manifolds and began to sell casting kits for the engine. A few years later the rights were purchased by Coles Power Models in Ventura California where the kits were sold until they went out of business in 2017.