1966 Dodge D/Dart ~ 'Mystery, Myth and Misconception'

Correct

Originally, the 1961 Corvette 283/270 HP 'Dual-Quad' came equipped with the
#3774692 'Power-Pack' Cylinder Heads.

Casting Mark > Rectangle w/Pyramid on top

That Cylinder Head came thru with 1.74" Intake Valves and 1.50" Exhaust Valves.
They had 'medium size' ports {137 CC Intake} and {57 CC Exhaust}, along with
tight combustion chambers from the Factory {Minimum 59.7 CC}.
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In 1964, the NHRA permitted the use of the #3782461 'Fuelie' Cylinder Heads on
the 1961 283/270 HP Engine.

The 'Double Hump' casting Cylinder Heads had 1.94" Intake Valves and bigger ports
{160 CC Intake} and {62 CC Exhaust}.

The Combustion Chambers were bigger {62.07 CC}, but the NHRA permitted them to
be milled to {59.7 CC} for the 1961 Corvette 283/270 HP.