The only safe way to deal with that spring is to extract the regulator assembly and do the install job on a bench. When correctly installed that spring, because of what it does, contains a signficantly large amount of energy. if it coiled up and pops free, it can bounce all over the place inside that door shell, and you don't want to be around one if it does goes flying as it will sail from one side of the shop to the other and get very lost in the process. The 8767........... version of the spring in those pictures might be closest to what you need.
To ge the regulator out you will need to dismount the window and then drill out the 4 Cherry Q split rivets that hold the mounting plate to the inner door skin. The two arms will have to be sild off their tracks and you may have to move or remove a few other bits. To rehang that mount, well. 4 1/4 inch x 38ths bolts work as well as anything. For the passenger's unit on my Monte, while I had the regulator out, I tacked the nuts into place to save the hassle of trying to fish them and deal with the bolts at the same time, but that is me being me.
With the regulator on the bench you can use a large pair of vice grips to clamp that toothed arm to the base. That part is IMPORTANT!! if you don't secure that arm it can act like the blade of a pair of scissors and snap closed.once the spring is wound and slipped into place. Should you have a finger or hand in there when it does, you will get hurt (Ask Me how I know that for a fact)
During all of this, to fix the lack of video or on line manual instructions, you can always turn author and do it yourself and post the results!
For the factory how to, you'd need the factory service manual for the body/cabin. Back then it was all one book and you can get them from Faxon Literature out in Californis.
Nick