At a GM dealership expect to pay $800 for a new upper and lower gasket change. The $1700 comes when the lower aluminum intake manifold needs to be changed at the dealer too. This can happen if the aluminum around the coolant passages gets so badly pitted that a good seal can no longer be obtained. Sometimes GM will sell you a "revised" Series II lower intake manifold for several hundred dollars to provide you with a reduced diameter EGR stovepipe that you can buy and install yourself for $20! Plus- GM and most shops won't sleeve your upper to keep it from failing in the future.

Please read and see pictures of a sleeved upper at the first thread referenced.
http://www.bonnevilleclub.com/forum/...ic.php?t=33565
It will answer a lot of your questions. Don't even think of changing out the upper only. After you have gone to the trouble of tearing it down that far, unless the lower intake manifold gasket has been recently changed, you really must change it for a new one. I don't know what the ratio is, but from what I have read on this site, it seems like maybe half the failures are a bad upper, and half are bad lower gaskets.

If you install a sleeved upper, a reduced diameter pipe, and the new generation lower gasket, the chances are very good you will never have to do the work again on that engine.

It is good news if you didn't even hear the engine "cough" when you tried to start it. Hopefully, your rods will be OK.