Petersons "AMERICAN INDIAN TOMAHAWKS" has good illustrations as to how the originals were made.
One of the common methods was a simple wrap around head with a high carbon bit welded in, then a separate bowl with a saddle set on top and brazed on.
The book shows 4 or 5 different methods including the gun barrel type, and the punched eye.
I have been told that the entire book is online to be viewed.
It would appear to me that the bowl with a saddle on the simple basic tomahawk would be one of the easiest to successfully pull off, or simply adding a bowl to the wrap around head with the saddle just filed in maybe even easier.