I know they have been reproduced by a couple of different people over the years. I would keep a look out on Ebay and advertise on the typical Ford sites like here, Model T Ford Club of America, AACA, etc.
Hello on the Henry ford radiator cap! Did you ever find one and what do you know about them? Does "anyone" know anything about these Henry Ford bust radiator caps? thanks, Mike 503-622-3639 or email fordhavenzigzag@msn.com