That is correct......... '457' = 1967 Dart GTS 383 cars produced.
In 1967, the #2780915 Cylinder Heads with the 1.60" Exhaust Valves could be
found on the following >
* 440/350 HP > Chrysler cars {ie; Lebaron or Imperial}
* 440/350 HP > Plymouth Fury {I, II and III} Station Wagons 'only'.
* 440/350 HP > Dodge
The #2780915 '440 HP' Cylinder Heads came thru with the 1.74" Exhaust Valves