The Stovebolt Site Forums The Parking Lot Big Bolts 5.57:1 Ring and Pinion for T170 Axle - question on installation

Today I went and picked up the ring and pinion from Craigslist seller. It's got really minimal wear and is in excellent condition, save for the three teeth with some obvious rust on the drive thrust faces that Van Der Haag's polished up before selling it to him. Guy seems on the up and up, and he had the box from there, so I believe that Van Der Haag's shipped it as such.

So, Stovebolt hive mind, should I just go ahead and install this as-is? I certainly don't want to chew up the pinion, but if the rusted spots are lower than the rest, will they just hold oil?

Edit: the gears really aren't as brown as they look, they are dark grey but my camera's white balance and LED kitchen lighting make things look rusty when they aren't.