The motors in these cars run tight tolerances and, sad to say, you most likely are facing engine damage. The only sure way I know to check for damage is to pull the heads off of the block and check. I would recommend getting a copy of the Bentley manuals for the car if you're mechanical and going at it.
This is a big job. I just pulled the heads off of my car last week (week of Jan 5th), and it took a l-o-n-g time to get it all apart. This is way different from the 4 cylinder VW and Porsches that we're used to working on.
If you are going to rebuild, I have a set of 3.6 liter heads available. Hopefully you won't need them though.
