Mack, although I am always up for some good entertainment, I personally don't want this type of entertainment at your expense. I feel like if this was a suitable match for your quad, the manufacturers would be releasing it stating it availability for the 450 / 600.
That being said, I recommend you calling AMR and asking them if it would work. Just because the plugs will match up doesn't mean it will work, the same as a 700 Rhino CDI wasn't designed for a 700 Grizz, but even far more different in your case.
Attempting this without getting input from them that it will work can be a very costly experiment on your part as aftermarket CDI boxes change ignition timing curves. This could result in any number of potential hazrds ranging from it blowing your ECU to the worst end of the extreme of blowing your engine from the timing being too far out of wack for your application. There's a small chance it will work but and even grander chance that something will break, and will be very costly in the end.
Personally, this just isn't something I would recommend you trying without advisement from AMR.
Just my thoughts.