[Rick Parker]

The air pocket that you speak of is acceptable if it is totally collected into the tank. The air will seek the highest point in the system thus allowing coolant to displace it and contact the surface of the block or head and provide cooling to the contacted surface. The small hose from the radiator to the puke tank allows trapped air in the top of the radiator to be purged while coolant is filling the radiator.
I will go out on a limb and say that the Overflow tank as we know it was originally developed by Ford because the styling of the cars and radiator design incorporated in vehicles that had hoods that hinged at the front. It may have been that the heads in the "NEW" FE 332 in 1958 were higher than the top of the radiator and was necessary to allow the air to be purged. The tanks were not used in pickup truck applications maybe because of the ability to install taller radiators (?).