You'll be fine with the 4.10 8.8" rear from NTO. This is the one you want. It's got the pinion flange for the V6 already installed, and will be a pure bolt in installation. You won't need to to anything at all to the vehicle, or the axle to make it work.

As far as that differential cover goes, you'd be wasting time and money, unless you REALLY want chrome out there. You'd need the requisite gear lube, and friction modifier, and some RTV to seal the gasket. I say skip it.