Sounds more like the rings never seated or the cylinders were scored.

 

Do a compression check to see if the rings in that cly are leaking or much lower in pressure than the other one, sounds like a ring problem to me.

 

This is what it sounds like. Using that much oil that quick and becoming that dirty leads me to think lots of blow-by of the rings in both directions. For some reason the one cylinder's rings did not seat. Probably the shop did not do a glaze busting of the cylinder after putting in the new rings and pistons, assuming they used your original cylinders and bore. With a glaze of the bore (depending on how many miles you had on the engine prior to the build) the new rings seat slower or not at all.

 

I was told by my dealer today that a too lean condition would result to bad valve seals. Is that correct? I did a stage one from Fuel Moto and wouldn't that richen up the fuel?

I having the same issues too with the oil consumption.