Very cool !
I see they did the one test with a 707, probably because needing out board engines on that test bed also,, ''just in case''...
My Pop's worked on the 707 project a bit @ Boeing, in the late 50's.
One test Pilot actually did an ''effortless'' barrel roll with one of the prototype's in front of Boeing during a press ect. demo.
Bet your Dad knew about that one ''desert rat''.

Didn't even stress the Airframe at all.

Think it freaked out some of the ''VIP'' passengers for a few secs. though … LOL !!
Watched a documentary around 10 years ago,, on the ''static mount'' testing of the ''Triple 7'' - ''large'' engines.
They were throwing chickens & all kinds of crap into the inlets,, to see what would happen..

LOL
Those engine are frigg'n tough !!