Yes, those are the center caps. There were on ALL 1967 Chevrolets equipped with power disc brakes--> Camaro, Nova, Chevelle, Corvette and of course the full size line. These were used for 1967 only. The center caps currently on your car are for 1968 and up cars. They are known as "derby caps".
My first 1967 Impala SS convertible was originally Butternut Yellow. Unfortunately, the original owner had it painted dark blue. I sold that car it had lots of rust and crappy body work problems.
I too, am infatuated with the 1967 Chevrolets.
1967 Chevrolet Impala SS convertible - Ermine White C1
1967 Chevrolet Impala SS 396 - Marina Blue FF