Yes, you can swap the rangefinder elements, but you will need to recollimate the rangefinder after. It's easier to just swap the entire prism assembly and its retaining ring than try to remove the glass itself, as it has a very small internally threaded retaining ring that requires a custom spanner. The rangefinders were not changed, as the focal length of the lens did not change when Kodak switched from the Compur Rapid to the Supermatic.
The first Ektar lenses found on the cameras with the Compur Rapid shutters were uncoated, by the time Kodak switched to the Supermatic, lenses were being internally hard coated with Calcium Fluoride. Postwar Bantam Specials will have inside and outside coated lenses with Magnesium Fluoride, and these are distinguished by the blue violet coloration of the lens. I don't believe Kodak ever put their Luminized trademark Ⓛ on the Bantam Specials, but I could be wrong as I have not extensively observed known examples. Some prewar Ektars found on the Compur Rapid shutters may also be internally hard coated, but I have no source to confirm this.