Regarding Central Javanese inspired Palembang blades, it is very interesting for me to notice, there seem to be no switch to "internal" greneng till the end of Keris production there, the greneng stays external like on older Javanese or Bali blades.
Also interesting, there are Palembang blades of nearly the same age with both squarish and Solo style Blumbangan.
Here is a link to detail pictures of a good Javanese inspired Palembang blade (please scroll down, yet also the whole thread is very recommended)
http://www.vikingsword.com/ubb/Forum.../000307-2.html