Thanks!
I had a set of five lug spokers set aside for this project, but I got around to measuring them and noticed they scaled out to 18 inches in diameter.
I found one 15 inch wheel in my stash that will work with the tires I plan to use. But my wheels were five lug and had the factory center cap.

So I milled off the six lugs and center cap and machined a copy of what was on the truck for the center cap and lugs. I’ll cast copies.