I bought an '89 LS with 170,000 miles on it -- she's blowin' more blue smoke than I counted on ('bout 1 quart of oil/300 miles). I'm 90-95% certain it needs a valve job (runs great, just pollutes way too much, esp. just after laying on the throttle after coasting).

My main question is: Assuming it's in relatively good shape, how well can I expect the bottom to hold out if I throw in a rebuilt cylinder head?

I've read that the increased compression of a rebuilt head can cause the already worn piston rings to fail. I know the original owner, and believe the car to have been driven conservatively and well maintained.

Anyone go through this?
Do I bite the bullet, and drop in a used engine?