Old Mexican or Texican Bowie Knife

Old original Bowie-style fighting knife believed to date from about 1820 to about 1880 and perhaps from the region of Sayula, Mexico. Blade is marked with engravings and stampings from what I believe are two different periods. In landscape position (parallel to the cutting edge) is the wording, "VIVA (standing horse with undecipherable lettering below) MEXICO" followed by lettering perpendicular to the cutting edge, "Mc" with the "c" in superscript. The "Mc" is deeply stamped (and perhaps the horse) so I believe these deeply stamped marks are original to the blade; the "VIVA MEXICO" is chiseled into the blade and I believe date from a later period. It is my perception that these later words were added on as a defiant symbol on what perhaps may have been a war trophy or otherwise acquired knife; I suppose it could just as easily be from a Mexican "patriot". In any event, this knife could have been carried during the Texas Revolution, the Mexican War, the Reign of Maximillian, the Texas Frontier times, or all of the above.
Appears to be blacksmith made with a rudimentary bird's-head pommel (some design appears added to make it look like an eagle); old horn grips with iron attaching pins; blade has a nice ring to it.
Overall length is ~16-5/8"; blade length is ~12-1/2"; width at choil is ~1-7/8", at ricasso ~1"; thickness at ricasso is ~1/8", at tang ~3/16".
Fair condition overall.