Those are my favorite 8-lug center caps, the original smooth. Red will look good and you can always change the color.
I play around with color on my stuff from time to time. On my '92 K3500 I went from stock wheels with those center caps (and beauty rings) to 7" Accurides with 76-91 hubcaps. I painted the wheels the factory color for a "Is that factory?" look. Then the wheels went on my '95 K2500 Suburban and I painted them charcoal to match the early W/T grille I have yet to find. It's too dark anyway, darker than the Cheyenne grille. I was really wanting a gun metal shade but used off the shelf color. Now I want to go back to the rallye wheel argent. Thought about white for an even more retro look, but plain Jane stock utility is what I'm after.
Yeah, these are '90s trucks. But this is about wheels. And red it is. But this can help future referencing. So for some comparisons with all the same wheels except the first one, that is what he has now.
EDIT: I even had the same wheels/tires on my '72 a while, for another example... w/o caps