Hi Michael. I have been sitting back waiting for more knowledgable members than me to comment on this keris. I would think that Kai Wee or Shahrial would have a word or two on this one. I feel a bit out of my territory with keris outside the Jawa/Bali/Madura circle, but i still want and need to know so much more.
That said i would certainly venture to say this keris is a mixed bag. I am not sure it is always fair to say such combinations are "dealer mixes". Sometimes a blade legitimately moves from one region to another and gets re-dressed appropriately for that region. Sometimes a blade from somewher like Jawa will be imported into another area of Indonesia. Not saying this isn't a "dealer's mix", just can't tell.
On the blade i would vote for Sumatra and the sheath, Sulawesi, so i guess i am with the majority here. I don't know much about this hilt so i couldn't say.