No the decals are original factory fitted items.
Each engine option had a correct decal based on its family (L6 or V8)
and its rated horsepower. i.e. Turbo-Thrift, Turbo-Fire, Turbo-Jet with crossed flags on big block 396 engines, etc.
I think if I remember correct most if not all the small block V8's were Turbo-Fire,
Big Blocks were Turbo-Jets, and the L6 was the Turbo Thrift but I'm not 100% sure.