I dont think it could be confused with anything else except a Frio. As far as regions, Check it against the Frio on the fence post that D&K just found North of the city of Sabinal. The original owner may have been on a hunting party well away from home.
I'm not good at all on IDing the flint itself for source, someone in the know might tell where the flint came from as an indicator if it was made up North or carried there.
Nice pics ( "insitus" always convey the joy of the find )