1967-1969 Chevrolet Camaro SS Campbell Ad Agency Magazine Ad Concept Boards / Proposals - Info ?

Hi,

I'm hoping to learn more about some items I recently acquired. These are original advertising agency mock-ups / proposals for Chevrolet Camaro SS / Nova SS / Chevelle SS magazine ads. According to the seller I purchased these from, they originate from the Campbell Ewald ad agency, which makes sense as they were Chevrolet's agency during this time. They aren't marked, however, so I'm not certain.

These items are rough mockups - 2 are hand drawn and 2 are 'collages' with cut-out images glued to paper. The cut out images were clearly done by an artist using a fine knife as they are extremely neat and trimmed very professionally. Other than the main slogans, they use lines or lorem ipsum as place holders for text not yet created. I have collected literature for a while now and have never come across anything like these - they're really an incredible view into the behind the scenes creative process at the time.

The four pieces are:

1) 1969 Camaro SS - hand drawn with the slogan "To come close to Corvette, we picked the best sports car brains around - our own'. I've seen this slogan used before but never this type of image.

2) 1968 Camaro - hand drawn with the slogan "The cars you hate to get out of". This one included a very rough concept sketch which describes the figure to be included as "an older sporty (Barry) Goldwater type with a beard and large sunglasses"

3) Collage image with the slogan "Chevrolet Builds them Healthier". Ad was to cover Nova SS350, Camaro SS and Chevelle SS 396. (1967/68?)

4) Collage image with the slogan "Chevrolet Turbo-Jet V8s are what put the soup in super sporting". Covers Camaro SS and Chevelle 396 (1967/68?)

I was hoping that someone here might be able to provide more information about these proposed ads - who created them, where were they intended to run, did these proposals (slogans, designs, images) lead to any actual ad campaigns?

Thanks in advance for any insights or theories!