Here are two hammer poll tomahawks that are “supposed” to be circa 1775 and 1780. The round poll hawk is allegedly dated to 1775, and the square poll hawk is allegedly dated to 1880. The square one is more of an "axe" in appearance, so it may be more what you are after.
According to information I was given these are/were from the Hendershot Museum, although there was some suggestion the 1775 round poll hawk was from a private collection. I dug these pictures up when I was looking for a pattern for the hawk I had forged for myself. As I recall I did have information somewhere that seemed to confirm the dates of these hawks, but I can’t remember where it was. I’ll see if I can dig up that material again so you have a reference. Somewhere around here I have measurements and dimensions for each head.
This is the round poll hawk (1775)
This is the square poll hawk (1780)
Either way they are pretty cool, and while the dates may be somewhat in question, both are authentic in apperance for that time frame. I have one custom forged that is a copy of the round poll hawk.