bone nut

I just bought a used Tremonti and it is currently set up with 12s in drop C. I assume the nut will need to be replaced to get back to the 9s that it originally came with. Looking for the best/easiest replacement, buy a core or tusq? Other?

Hey fellow PRS friends, I'm having some issue's with tuning stability with my 2011 Custom 24. When I first purchased it brand new, it stayed in tune incredibly well. After a few years of owning it, I decided to have a bone nut installed by a mediocre guitar tech. After she botched the job and...