If you expect steam in your coolant passages, you should also expect trouble. Jim Carter started the steam-hole/steam-vent foolishness and it has persisted.

GM referred to the six extra coolant passages in the 261 block/head as water holes and here is a discussion on 235-head drilling angles.

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.