There was an organization called "Kits and Plans Antiquitous" which is now defunct as of sometime after the 1990's. They had a quarterly newsletter called "The KAPA Kollector". The organization was devoted to, as its name suggests, the early years of model aviation. The June 1997 issue of The KAPA Kollector was devoted to Walter Musciano and included 50 pages. This included an 8 page history of Musciano written by him. Then, it showed the half century of Walt musciano's designs, articles and books which took 8 more pages to list (typed, single spaced). Included in that listing was all of Musciano's Scientific kits. Lo and behold, there is a "Kingpin Jr" for 1/2 A (profile and built up-wing) and a "Kingpin Sr" for .15 - .29 (carved fuselage and built-up wing). The wing span for each of these models is not given.
The December 1998 issue of The KAPA Collector was 24 pages, all about John D. Frisoli and Scientific Models, Inc, written by Walt Musciano. This included a 3 page history of Frisoli and the Scientific Models company. Several pages showed a sampling of the Scientific advertisements in the model magazines from the 30's through the 60's. Also included was a sampling of the plans that came with these kits and photographs of those models. Unfortunately, these pages do not show or make reference to the "Kingpin".
Keith