1920 Carbine, Less Forearm

[Anfanger]

Here is a "puzzelah" has Click and Clack the Tappet Brothers used to say: Could this be a 1920 Carbine, Less Forearm?
This is from my recently acquired collection.
Referencing "Lugers at Random" by Kenyon, and "Luger Variations" by Jones, and trying to find more guidance here on the forum and on Mr. Still's forum, please help with further insight about the attributes of this Luger.
I've had a discussion with Jerry B., and he's seen these photos, and thought perhaps it was a "Long Barreled Luger", but the ramp sight and 3-4 position rear sight have us leaning towards the "1920 Carbine, Less Forearm" as described in Jones' book, on pg. 159. Jones also says this variation is often called a "Parts Carbine".
Numbers match, except for the side plate, which is "91", and the barrel is stamped "11" in the space between the metal of the rear sight on the underside of the barrel.
Barrel length is 11.93", which is within the range listed in Jones.
Thanks again to all who make this forum such a wonderful resource.
I look forward to reading your comments.
(I know is has the chunk out of the grip - I didn't do that!)