Easiest way to tell them apart is the valve side cover. It is all the way up around the spark plugs on a 216 and only aboyt 5-6" tall on a 235. And also the 216 did use two center valve cover studs and nuts but adaptors are sometimes used to keep that look on later 235 engines as when an Offy aluminum cover is used. Mine is that way so the valve cover check is not always correct unless you know the rest of the story.
Not nearly as confusing as it sounds once you get the hang of it.
