I've never seen an assembly manual. Can't comment on whether it would help. Probably couldn't hurt. But the fact that you're taking the car apart should make it easier...the factory workers didn't have that benefit of starting with a whole car, so they needed a manual to tell them how to build one. Maybe you don't need one? I never have...but everyone is different.

Use a camera and take good notes. Torque values for bolts should all be in the service & body manuals you already have.

What info have you found that is missing? People here can likely fill holes or answer questions.

Chiltons and Haynes manuals are good for toilet paper in a pinch, and maybe packing material. Little else. Expect nothing of value with those books.