Saab - 9000 :: 1997 - Loss Of Oil - Head Gasket Is Leaking?

I have a 1997 Saab 9000 CSE Turbo. It has been a great car overall. Last summer, our water pump died while cruising on the highway, leading to a major overheat, leading to warped head. We decided to roll the dice on a rebuild, which was done by a reputable import specialty shop that has worked on many Saab 9000s. Since we got the car back 5000 miles ago, we have lost a few miles per gallon, and we hear a rough noise in the engine (particularly when it's cold). In the last few thousand miles, we lost a lot of coolant, apparently because the new water pump is faulty (the shop looked at it and agreed to replace under warranty). In the last 1000 miles (but no evidence of it previously), we have begun losing oil like crazy and occasionally (but not most of the time) smelling burning oil (the heater is on, moving air around). We are now adding about a quart per 200 miles. When we inspect the block, there is some small evidence of oil leakage, but not a lot, and there are never drips on the driveway.

Where is all that oil going? I showed it to the shop, we put it on the lift, and there is no spray on the underside, leaking oil pan, etc. I suspect the new head gasket is leaking, but there is little enough residue on the block that it's hard to be certain. What other explanations are there, and is it fair for me to blame the repair shop and insist that they redo the head gasket? The shop is a 6hr drive from my house, so I can't just drop by to discuss it with them.