When I was in high school building Chevy engines, we found that if we took older engines and rebuilt the heads, then the improved sealing on top made the weaknesses in the block more evident. There was more oil consumption. That was an american iron experience and I know VW enthusiasts often rebuild just the head finding that the bottom half is barely worn even when the odometer has reached six figures.
VW Short blocks are known for their longevity, but I suspect since many of our engines are well over 10 years old, that you may have a similar condition. A fresh top end may be exposing some of the internal wear and tear on your short block region forcing oil to be passed between aging seals and rings. The amount of oil you describe indicates you will need to focus some attention on the cause(s). -Les
