I think the biggest problem you're going to encounter is the fact that the right-hand drive Fugas have the button layout flipped from the Left hand drive M's. Even for the climate control functions. So unless you can find a right-hand drive Infiniti M button pad, I'm not sure it'll be very functional. And as far as I can recall, all of the countries that get the Infiniti vehicles vs. the JDM cars, are all Left-hand drive. If you're handy with wiring, it probably won't be a problem. You're probably going to encounter issues with the wiring harness seeing as Infiniti's use traditional GPS nav services, and the Fuga's use "Carwings" pay service, etc. So they are more than likely wired completely different.
I may be WAY wrong and off base here, but at any rate I hope you're able to do it! It sounds like it would be a fun project