Also, if I can be blunt, I had a Cantrell-modded Fish (actually the one @itsgoodnow mentioned above) paired with a VHT 2150 power amp, and while it was very cool, it's not a tone I would spend that much money chasing. You can get that tone from other amps out there at lower prices that are much more versatile. For example the Headfirst Alta 100 with the Clip and Bright switches engaged in Modern Voice will get you 95% of the way there for a fraction of the cost of a Cantrell-modded anything, and you'll have a kickass amp that does a lot of other tones to boot.
The Cantrell mod also kind of "ruins" your amp. There's no way to turn the mod on and off. It just turns your amp (whether JCM 800 or Fish) into a flamethrower that really does only that one thing. (Save for the fact that you'd still have the other channels on the Fish; but, TBH, the Brown channel on the Fish is 80-90% the same sound as the Cantrell-modded Shark channel anyways.)