I appreciate y'all's input! It sounds like we're all pretty much on the same wavelength.
My initial plan was to replicate this truck's paint, possibly with a bit more white:
I even picked up some Tamiya Coral Teal (or whatever it's called). But I felt it was too close to blue and I really want to change my trend of blue vehicles. It's also too close to the color of my Defender D110. Told ya I have an issue with too many blue rigs!
My plan was always some sort of two tone with a primary color (TBD) along with a white or off-white. I don't want any metallics, though. I don't think it would look right as metallics weren't common on trucks in the '50s. I was leaning to red/white like the truck below (but with a gloss finish), but I'm rather intrigued by the brown/tan idea!
One thing to note... It's going to be difficult to paint the grill like an IH given the shape of the Zil's front end. So I was leaning toward painting the whole front clip in white.....like this, unless someone has a better idea?