Yes diff flipping would be a requirement with most common diffs available (I'm not aware of all their rotation directions though), I honestly don't believe there would be any oil feed problems to the bearings with so much being thrown around and overfilling the diff is an easy option.
In street use it's usually not a big issue but in high load offroad or track use, well. .. Then it depends on the internal shape of the housing.
In a large percentage of what's available (such as a dana or iirc, a hitachi, my memory seems to be fading faster in the last few years) the ring gear slings oil onto the interior face of the diff case above the pinion bearing which has a cast pocket feeding a weep hole going to the outside (leading face in the oem driving direction) of the pinion bearing but behind the pinion seal.
The oil then dribbles through the bearing and back into the bottom of the diff, it doesn't take much having only rotational loads.
The problem with overfilling is windage losses.
Again, not usually a big deal but if you're looking for that last bit of available power the losses increase as the rotational speed increases. Even 70w is some pretty heavy stuff.
It's not that the "lube fog" from windage doesn't work, it's just that in high stress use the lifespan is greatly reduced because the front edge of the bearing gets almost none and then it's from creep not direct supply.
Rotational direction should be a piece of cake for someone with your already proven skills dude!
I'm a kinesthetic learner so I have to use my hands to get it but anyone that can build cars in a small shipping container is pretty darn good imhop.