I've never seen a neoprene seal for a 216 or early 235. The groove for the seal in the late 235 with the rubber seal is narrower and not as deep as the one for the rope, so if a rope is used it will lock up the crankshaft. A neoprene seal in a rope seal groove will not make good contact with the crankshaft and it will leak immediately. Best Gasket is the ONLY rope seal I'll even think about using. When the tree huggers raised such a stink that the asbestos was removed from crankshaft seals, they quit working right. I don't know how Best manages to make theirs work, but they do it somehow.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!