Yeah it could be 54, many of the emblems only ran 2 tears, with a few exceptions. I havent been in that business since around 84 so am a bit rusty. The one in the first pic had decals which is a bit strange, as most Hummers shared the same metal badges as the big ones..
The Hummer and Bamtam was a spoils of war sort of deal.
I cant really agree with Ichaban, I see many 50s H-D's on the rad but not so many british bikes..