A leaky turbo would fill your intercooler with a ton of oil too. How you explained everything and the look of the rotor and plugs indicates an internal oil issue. Sounds like you got it nailed down. Did they use new vitons when they rebuilt it? Looks like your engine will be good to go for a good long while after this. The ports don't look too large... It is very close, and you can see where they went a bit too far on the primary port but it should be alright.

 

This is a cool read. Keep us updated when you get it all back together. It's always fun to hear when someone fixes their problems!