This kampilan was sold at auction in 2013, it was deaccessioned from the John Woodman Higgins Armory Museum in Worcester, MA. It has a strong provenance from an American army officer who served in the Philippines between 1898-1899. It also displays the Type I Maguindanao hilt characteristics you listed above, Ian. Unfortunately its owner was posted in Jolo and several other locations in addition to Maguindanao and was not specific about where he acquired it.
http://www.auctionflex.com/showlot.a...enum=1&lang=En