Fleece blanket fabric is great for this. Solid or with a pattern, and use the 3M adhesive. There are videos on YT that show you how to apply the fabric without wrinkles or sticking to itself. Might want another set of hands.
That Cummins tan is sharp. I just did my valve covers and intake in red, but that has a clean, industrial look to it.
I’m sure you’ll drop the headliner, but be sure to check/reseal the roof ribbing....they rust under the rail and pinhole leaks eventually start. I actually had to cut out a few...