I've also been contemplating to do that Battara!
I didn't notice that Gayo keris also uses selut Gustav. Very interesting!
It seems that this selut/pendongkok were found where ever the Bugis sets foot on.
From Sulawesi, Ternate, Bali and the Malay Peninsula. So, it is probably safe to assume that this style of selut is probably Sulawesi style since we also have a dated example above form 1749 which is a keris with Sulawesi dress.
Anybody know why the rubies in the metal detector selut are oddly and shaped? The shapes are different form each other it looks like naturally formed?