Green, here is another link about Tok Chu keris that you might find useful.
http://www.vikingsword.com/vb/showthread.php?t=7618
One other point i might add to you initial question. My understanding (please correct me if wrong) is that Tok Chu was producing keris sometime around the end of the 19th century, so relatively not really that long ago. Your keris shows erosion and wear that if genuine would probably place it's origin before the time of Tok Chu. If anyone has any correction to this information on the era of Tok Chu i would appreciate it. My info comes only from "word of mouth".