my '64 chevrolet Master parts book (covers '62 235s) only shows casting numbers-no dimensions. The book says '50-'62 intake L casting # 3764485; exhaust L casting # 33764487; intake R casting # 3764486; exhaust R casting #3764488. All the 216s are different part numbers than the 235s so maybe you were given a 216 rocker. As with a lot of things, later could mean "bigger" diameter rockers and shafts.
In your bottom-most picture, the end rocker has a Square outline with an "M" in it--that may be an old Mellings logo-they made cams, oil pumps and a lot of engine parts-rocker could be a replacement part--235s with bad oil changing records could gall rockers and their shafts from sludge clogging oiling to the rocker shaft necessitating replacements within their lifetime.
Thats alot of scrap iron to be towed around with a lowly 235! Is it a stick or a PowerGlide (may be the first year for an aluminum PowerGlide-either '62 or '63. Does it have an alternator or a generator- I think the factory a/c cars had the first alternators, "sweatbacks" were stuck with the last of the generators, in '63 all had alternators. Good straight body and trim!
