1950's Chevrolet Dealership Window Poster

I got this Chevrolet paper poster from my grandfather who was a Chevrolet dealer in Iowa back in the early to mid 1900's. I believe it has been in a folded condition for at least 60 years and due to it's condition was probably never displayed. It is not dated but could be from around 1955 when Chevrolet introduced the V-8 engine(more power). It measures 30 inches tall and 60 inches long. It is stamped Litho. in U.S.A. and the artist name is Chas Allen. Charles Allen was an advertising artist from California. I have emailed several people who knew the artist and his works, but no one was familiar with this poster. I have also looked at over 700 examples of his artwork and this poster wasn't included. One of a kind? Not really sure what I have but it should be framed and put up for display somewhere.