Western Autos and Seiberling were both companies competing in the same commercial arena and both offered lines of bicycles supplied to them by a range of individual bicycle manufacturing firms. The use of the name Roadking on your bicycle’s badge and the use of the same name in the Western Autos literature is really just a naming coincidence occurring between two separate companies. The monikers “Road King” and “Road Queen” have probably been used as names for bicycles many times since the 1890’s in catalogs and/or on badges and do not alone carry any real or implied lineage between those so named units.
The excerpt you posted from the NBHAA is referring to the cataloged model lineup sold by Western Autos in 1940 and 1941. Those bikes would have been branded with Western Flyer branding or badges while, in the catalog, they would have been given additional names and/or model numbers to distinguish them from each other.
In the case of your bicycle, the actual manufacturer was clearly Cleveland Welding and the final retailer was clearly the Seiberling auto and tire supply chain. Your bicycle is also separated in time from the NBHAA description which refers to 1940/41 while your bicycle is from 1947.
Seiberling was a smaller chain than Western Autos but I have seen some of their catalogs. If you are looking for more information pertinent to your bicycle you could keep an active search on eBay to try to locate a catalog that might help or you could contact the NBHAA to see what they may have on the early postwar Seiberling lineup.