I doubt you'd find anything, as it was not an incident, if the A/C did a 3 engine ferry (no pax) from an airfield with no engineering support to the most suitable airfield the only way to lock the N1 is to strap the blades to outlet guide vanes as in the pic, they are not seat belts and it's clear rubber strips are under the straps to prevent the straps from being damaged.
What you should search for is the Boeing recommended technique to secure an A/C engine for a 3 engine ferry when engineering is not available to remove the blades to prevent N1 from spinning.
To three engine ferry a RB211 you have to remove the fan blades and fit a fairing over the core intake. It is proberbly much the same proceedure on the CF-6 and JT-9.
You can also ferry a JT-9 with the fan blades "Gagged". In this proceedure you tie the fan blades to the stators behind it. The approved tool for this looks like a very long passenger seat belt compleate with the buckle assembly!. I have seen "Shock, Horror" report of this in the "Gutter press" . You know the thing "Aircrafts engine held together with seat belts". But it is an approved M.M. proceedure for the JT-9 . The other thing with this method of ferrying is you have to gag the core to prevent it windmilling. This is done buy removing the hydralic pump and fitting a gag to the pump drive.