I am a original guy myself but when I got my 49and52 pickups I know to get rid of the 216 I don't know the true term for it but i call it a half oil system it has these little tubes that spray oil on the rocker shafts. I don't know if this is the case always, but I know the 216's valve cover is held on with two acorn nuts on top of the cover. and I am pretty sure the 235 and 261 are held on with four valve cover nut down by the base. hope this helps and if I am wrong the folks in here will steer you in the right direction.
