If you can, it'd be worth getting in contact with Warmoth and seeing if they can make the neck stock out of korina. Necks can be made from both white and black korina, and though it's not a common Warmoth option, I'm pretty sure they have done it in the past and only don't have it listed normally because it can be a little hard to get hold of korina suitable for necks. But you never know, they might have some suitable korina in stock. You could then have that finished in the same colour you have the body, so the back of the neck and the body will match perfectly.
For fretboard, ziricote can have colouration similar to the darkest of black korina, and it's got a bit of a red undertone to it, like some rosewood can have. It's pretty dense, so it should keep the sound a little brighter. Depending on the actual colour of the body, and going with the theme of matching the neck to the body, either bloodwood or padouk would match, depending on just how bright the body is. (Bloodwood would match white korina more, padouk for black korina).
I'll say this for tone: One of my builds, at one point, was a black korina Thinline telecaster with an all-rosewood neck. It was a thick neck, too, and 24.75" conversion scale. I've actually taken that guitar to pieces now and am using the neck elsewhere, because the semi-hollow korina and rosewood combination actually was still too bright, at least for my tastes. Not as bright as a normal Thinline Tele, but still much brighter than even bog-standard set neck solid body guitars.
I you're going to use single coil pickups, or lighter, lower-output humbuckers, I advise you don't worry about the tonal balance of the woods much, because the tone of korina, combined with bolt-on construction, isn't actually that much different than your typical alder-bodied bolt-on. If you're using thicker-toned humbuckers then you might want to stick to the denser neck woods, but I still doubt it'll make much of a difference. If anything, I'd pick the woods you like the look & feel of and then pick your pickups to get the tone to where you want.
