Interesting sword, Robert. I like it very much. I've got little to add to the prior observations.
I agree with Ian that the blade profile strongly resembles that of a
parang nabur. The handle is similar to some I've seen (
parang nabur without knuckle-guards are, apparantly, rare but not unknown), but the angle of mounting is unusual for that sword, and may be partly responsible for a vague
talibon appearance.
The scabbard is not very helpful, nor is the monkey skull. The scabbard construction of two pieces of wood bound together by plaited rattan appears across SEA, as do monkeys (anyone feel confident enough to take a stab at identifying the species?
).
I'm going to default to a generic "
golok" for this one for the time being.