Need a couple measurements - Horn Cap

[HAULIN' IT]

Guys, I'm working on a steering wheel for an "alternative" make vehicle (Studebaker) & want to use a round chrome cap for the horn. What I am hunting is a rather obtainable re-pop or whatever cap that fits the wheel & will modify the cap to include the original Studie emblem. It needs to be an "exterior" type (with a side lip that shows, not one that gets pushed down into a hole). Does any of the 67-72 have something like this...seem to remember seeing a smallish round cap on some of the wheels?

Can someone give me measurements of the outer diameter of whatever horn cap you have (with the year its from) & also how big the emblem area is to see if I can cover it with the original one?

Doesn't have to be a truck (or even a GM for that matter) just available & not break the bank...early Camaro, Nova, whatever someone can measure for me.
Thanks for any help, Lorne