I was just getting ready to suggest old cloth shutter cables from Ebay. You can see which ones have short fittings, and they're always really flexible. Then you threw in the self-cocking shutters. . . . for those you need a long enough firing pin that you can see will not fit in the space you have for it.
How about an alternative? If any of your lenses are longer, like 10" or more, you can make extension box lens boards to mount the lens out flush with the front of the camera, where you can get a release on it. You can quickly tell which lenses will work this way by racking the front in all the way, and holding a lens in front of the camera seeing where it will focus on infinity. If that's far enough out, you can do it. I make these boxes out of 3mm plywood from Dick Blick, cutting out all the pieces, gluing with yellow glue, clamping by holding the pieces together with masking tape. Then I wrap them with cloth tape, both for looks, and in case my glue job decides to fall apart the tape will hold it all together. Color the inside with India ink.