Alot of good suggestions here, I'll try with my two cents.
I would say, with the amount of vacuum, oil is being sucked into the combustion chamber. Valve stem seals are very good source. But, these would be more noticeable when throttle is opened up.
I would do a cylinder leakage test. This will show 1) how much cylinder is really sealed, 2) if there is a gasket leaking, see bubbles in coolant.
If cylinder is not sealed good, you'll hear air escaping either at: a. carb, intake valve leaking, b. tailpipe, exhaust valve leaking, c. crankcase (oil fill tube/cap), leaking past rings, d. coolant.
A temp of 200 degF is not bad, hoses are tight, and it doesn't boil over.
I am on the side of the fence with a couple others here, rings may need to be seated. I'm sure you've broken it in correctly, 20-60 mph, WOT, in high gear, then coast to 20, repeat previous 10-12 times.
I would suggest this, go to a GM dealer and get a can of EOS, Engine Oil Supplement. It's made for new camshaft break-in and new engines. I use it in my '68 and Dually, a helluva alot better than STP oil treatment. I bet it will decrease comsumption, 1 quart/1K miles is good, when you start leaving an oil trail from the tailpipe, then it is a problem.
If the EOS helps reduce the oil consumption, then it's the rings.
Let us know what you find out,
[This message has been edited by Everett#2390 (edited 05-29-2002).]