When I rebuilt a late '55 235 many years ago ('73 or so) I used the rope seal. It was difficult to get it mashed into place and have the crank still turn. I believe I squeezed it in a vice and used a hammer handle tapped by other hammers to get it small enough. Ultimately this worked. At the time I did not know about the neoprene seal and it wasn't in the gasket kit. This lasted leak free for many years. Thirty years later when I replaced it with a neoprene one it always leaked some. As it turned out, the leak wasn't the rear main at all but coming from the back of the side cover where I couldn't see it from the outside. I had taken the flywheel off to check that it wasn't coming from the cam plug and saw that it was coming from above the cam. All this after I had replaced the rope seal.
