I think Palembang dress would be nice
Well, I believe the way you dress the keris if you are a Nusantaran, depends on where you are going to use it. If you are to attend a function, say, in Surakarta kraton function, you could use a ladrangan warangka and Solo ukiran / selut / mendak. Other than that, since the blade is a straight bladed tilam upih, any type of dress would be suitable, IMHO.