I can't check my laptop bookmarks right now but it might be on the Edgun.ru sight.
I assume you mean to un-thread the rear plug & thread it onto the males threads on the left side of your CGI?
Interesting idea. One less fill assembly to own & carry in the field plus it would have a better chance of working with the Carm pellet dispensers than the air tube extensions. I guess more shots as you can shoot your bottle down to reg pressure.
I've thought about 3d printing a shoulder stock that would carry my aftermarket Russian airtube in a similar position as the Leshiy 2 stock & then run a short section of high pressure tube up to the fill port.
Have you seen the Classic Leshiy with the stock bottle? I think the picture originates from Vietnam. I'll see if I can find it.