Thanks for the additional photos. It doesn't look like you should have too much trouble adjusting the fit to this sheath.
The new photos reveal features that i hadn't quite noticed before, like the fullers that run almost 3/4 of the way up the blade. Frankly, the keris appears even less Lombok in these last shots. This isn't t say that it is not, but i feel like there are some Bugis influence working in there. Of course, that would not be completely out of character in Lombok i suppose. Anyway, certainly not a Bali blade. It does seem to be a nice keris regardless of its exact origins.
I hear that you are strong on traveling with this keris to the Philippines, but i personally would not consider making such a trip with it. You really do risk the chance of running into trouble whenever you cross boarders with it. If i were you i would try my best tp keep the keris in the States and do the work on your own.
