That wheel shown is a later wheel than available on any 67-72. The 16" wheels were split rim and only 16.5s were tubeless type. There were larger wheels available,too. The 67/68 wheels used inner clips to mount the hubcaps. The hubcaps has a stepped inner lip required. I don't have a stock bare wheel photo or one of the back side of a cap. But,here is a stock GMC wheel/cap combo:
Here is an optional camper wheel (8.25 x 16.5) with inner clips:
