I just did this exact same mod on my bass.
I've got a Peavey Grind NTB6, but the setup on it reminds me a lot of Carvin's basses. With standard tuning I went strings through the body, but the mono-rail style bridge also let me string it through the back of the bridge without going through the body. I haven't got a lot of playing time in on it yet, but it seems to have worked out pretty well.
My biggest problem was finding an appropriate string for the F#. At .150 the Conklin string is a bit on the light side, but people do use it. The other problem that you have on your bass though is that if you tried to go any heavier than that you probably won't be able to thread it through the body of the bass. (you may run into that problem already with a .150)
I tried to save the original nut, but it was glued down so tight it broke when I took it off. I had bought two replacement nuts from Carvin before I started though. The replacement nut fit perfectly and the modification was easy. I just used an exacto knife to scrape out the sides of the slots a little bit. Take it slow and don't touch the bottom of the slot at all. You'll need all the clearance you can get with the heavier strings.
It did take a bit of trussrod and saddle adjustment to get everything into playing shape again, but after I got it all adjusted my action is now actually lower than it was before.
I really just did this literally last week and tonight will be my first chance to play it through a PA with plenty of power and big subs.
I hope this all works out well for you. Oh...and just a tip. Pick up a set of the Dean Markley SR2000s (the Will Lee set). This should match your string from Conklin perfectly. (they're the same strings)
