Should note that's a 707 that Tex Johnston rolled, not a 747. I'm not aware of any barrel rolls performed in a 747.
There were some unusually significant structural differences between the prototype dash 80 and production 707's, for example:
> The 132 in (3,400 mm) wide fuselage of the Dash 80 was large enough for four-abreast (two-plus-two) seating like the Stratocruiser. Answering customers' demands and under Douglas competition, Boeing soon realized this would not provide a viable payload, so it widened the fuselage to 144 in (3,660 mm) to allow five-abreast seating and use of the KC-135's tooling.
The 747s first airframe is at the Museum of Flight in Seattle, and you can _go inside it_. https://www.museumofflight.org/aircraft/boeing-747-121
Seriously, what were they planning to transport? Pixies?
I need that sign. ha