Nice keris. I believe you are correct to place this in Sumatra, but exactly where i will leave for others. I would call this an "old" keris in that it seems to be pre-WWII, but i don't think it is extremely old. Perhaps 19th century, though the dress may be a little later.
I would say this keris blade is of the Bahari type. This type has two larger brothers, keris anak alang and keris penyalang or panjang.
You can read more about these classifications here:
http://www.vikingsword.com/vb/showth...ghlight=bahari
Over all a nice and attractive ensemble.