I tried the exact same fitment and it was a decisive no-go on the front. It might have cleared the rear - can't remember. Tried the Pirelli P-Corsa's (60 treadwear!)- VERY wide for the size, made my 275's look like 255's. Sure would have been fun...
Tire pressure will likely make a bigger difference on the rolling diameter than the width increase. If the front tires are smaller will increase the effect due to heavy front end. The center diff might work a bit more than it's designed to, but have yet to hear of any related failures. Change that oil- frequently.
I run a square setup to keep things even as possible and for better handling.