Ah like a 4 door sedan? No its not planned as it had different proportions of the front and all that sorr of stuff
The real-life inspirations for the Kingsway and the Stirling (Jaguar XK and E-Type) used different variants of the same Jaguar XK engine, so it would be a logical thing to assume. Considering they are from two separate manufacturers in game though, the sound would likely not be the same, but similar due to the engine being a large inline six in both cars.
It might be fun to have something like the Rover V8, but that's a later engine and in the 50s you really only have Rolls/Bentley, Daimler and AC using V8s (also kind of Jensen and Allard using American engines), and the UK manufacturers were really big into I6s.
Top bar of this website, click on the "Discord" button. The mod should have it's own thread in the "showcase your mods" section.