What appears not to have been mentioned yet in this discussion (unless, of course I missed it "along the way"), is the center hole on 1967 Styled Steel Wheels. On 1967 original, 5.5" riveted Styled Steel Wheels, the center hole has a "notch" in it (picture attached). This notch is for aligning the Center Cap with the wheel. Original 1967 Styled Steel Wheel Center caps have a "tang" on them that aligns the cap with the wheel (next pictures).
Installing original 1967 SSW Center Caps on wheels without the notch (ie 1965-66 SSW or 1967 Repro SSW without the notch). would require removal of the "tang".
Hope this helpsw.
Bob