[A. G. Maisey]

David, its your keris, and of course you can do with it as you will, however, my advice would be:-

the join between the wood of the gandar and the infill should be irregular and of a darker colour, it would be possible to do a neat edge to edge infill, but it would be a very weak joint and in time it will separate; by feathering the edges of both the infill and the gandar hole and using araldite or similar a stronger bond could be achieved, however, in Jawa this hole would be repaired as I originally suggested, but it would be repaired with one of a number of different infill materials, rather than plastic putty, the plastic putty gives a better and more convincing finish than does the materials used in Jawa. What you are trying to achieve is a repair that looks like variation in the wood, a la timoho.

Javanese gandars do not usually use a buntut, when it is used it is simply a contrasting piece of wood joined very neatly to the foot of the gandar, this is occasionally done for artistic effect on artistic or high class keris, it would be 100% incorrect on this keris. I've noted the hole in the toe of the gandar, this is not uncommon in Javanese keris, when it is desired to fill it, it is usually filled with a slightly oversize wooden plug that is then shaped to a harmonious contour.

the handle is probably not glued, it is more likely to be held firm because of corrosion (rust) that has penetrated the cloth or hair packing used to hold it in place, there has been a lot written in these pages on freeing up a stuck keris hilt, possibly one of our better organised people here may be able to direct you to the relevant threads. If it is glued, the same methods will free it.

yes, it is entirely possible it might have once had a pendok, I feel it would restore to a more authentic finish without one, but if you do need one, PM me.

linseed oil and turps is a wonderful finish for gunstocks --- I used to make gunstocks in my misspent youth, and my father was a fine art cabinet maker, I do understand this finish--- the trad English gunstock finish was developed to permit exposure of the wood to inclement weather, we do not need this type of finish for a keris. The traditional Javanese finish is french polish, but on dress of a lower quality the finish is usually completely lacking, or perhaps only a bit of beeswax has been used. To achieve a good seal to the timber and a subdued, realistic look that does not obscure the wood grain, rubbed down Scandinavian oil is very effective. There is a problem with the name, because different manufacturers use different formulas, some use a combination of tung oil and linseed, some are just turps and linseed, others use urethanes as driers, some are all polyurethanes. I use Feast Watson which is a blend of polyurethane oils and waxes, this is an Australian company, I do not know the equivalent of their products in other countries. Its probably not a bad idea to use some good furniture wax after the finish has dried thoroughly.
Another really good product to finish a scabbard with is Birchwood Casey Truoil. This contains linseed and other unidentified products which I guess are probably driers. It brings out grain beautifully and after several very thin coats can be rubbed back to a subdued finish.
There are a number of problems with linseed oil and the old trad hand rubbed finish, some are short term, like the slow drying and the need to work on a finish for a very long time at spaced intervals to get what you want, the other is the tendency of a trad linseed finish to go mouldy in humid weather.
These days there are simply much better products available that will give you a better, more durable and easier to maintain finish.

the mendak is a perfect match to this keris, it should not be replaced.