Yep, the 261 head codes (supposedly) were:
3703570, 3836850 - 1954 to 1962
They might have changed the castings in later years - we are guessing?
They may have decreased the "deck height" by shaving the base of the head (or, the deck/top of the block)?
Let's hope we get posts with better explanations/speculations for the increased compression ratio
