Let me add this to the text. The only 235 blocks that a 216 head will fit are the 235 blocks from 1941-1949. The 1950-52 235 heads will only work on those years. The 235/261 engine blocks from 1953-1962 can all use a common head. There are some differences.
The 1953 235 heads use the earlier 216 style valve cover.
The 1954-62 heads have 4 bolts that hold valve cover on at the sides of the cover. The 261 heads have steam holes drilled to accommodate the Siamesed cyls
