I'm sorry to hear that Chris.
I'm sorry to hear that Chris. This problem is a real shame. This is the first car I've owned where I've had to add oil between changes. To be honest though, the safety, AWD, and other features of my 14' Impreza (to me personally) outweigh having to add some oil here and there, as annoying as it is. This is my first Subaru and other than this issue I love it.
I spoke to a family friend who owns a local used dealership, and he said that he doesn't feel any part replacement will fix the oil consumption issue whether it be piston rings or an entire short block. OW-20 is just so thin that it burns up and gets into any nook or cranny it can. This is also why Subaru switched to it, though it ended up back firing on them. They wanted to extend the amount of time between oil changes (the marked 7,500 miles) by switching to that oil.
I believe the only way to FIX the problem is to change oils entirely and make any necessary adjustments to the car's engine so it can safely use it. If you search NASIOC there are threads where people have reported switching to a slightly different oil and there being no negative effects on the car. Maybe that in combination with your new short block will be enough. Just keep in mind that would void the warranty.
Just some ideas.