Alam Shah,
I am impressed by your humbleness
On the gap I don't think it's that prominent.
When in the sheath it fits tight and doesn't move or "rattle".
But you are correct that there is some small space on the top of the sheath.
On Gayo Keris I think the best source is Sejr Jensen's book.
Obviously Bambang Harsrinuksmo thought so too.
Henk,
Is it the blade you don't think fit the dress or is it because of the pictures of the Keris in the sheath?
Do you have some other reference pictures of Indragiri style Keris and their blades as a comparison?
Indragiri has historical influences from Aceh, Java, Bugis, Portugal, India, Arabic countries, Holland etc.
Michael