Bart/Amos - I was only throwing out a suggestion, since I hadn't seen it mentioned in this thread. IMO, it would only take 3 of 12 really stuck to give those readings like that on a cold, dry, possibly tired engine. Or are those numbers for a "wet" test?
But my main point was, it's time consider a systematic disassembly and inspection, and the top end is easiest to get to, so why not start with making sure the valves are free (and move with engine rotation, as I think was mentioned earlier)? If possible, a leakdown test might be a better starting point, but it's likely to show all cylinders leaking at the valves from what you describe and have been working with the OP, so the V/Cs need to come off, anyway.
