All,
Thanks for all the opinions so far and for welcoming me here. The prebuy is complete and I've shared the info with a couple more A&Ps to get some additional thoughts as well.
Some shotgun answers to the various questions and points raised here:
-The prevailing opinion from the A&Ps is that the engine wasn't properly broken in when it was new, which is what led to the excessive oil consumption and the first pull of the cylinders off the engine. The second pull came from a lycoming warranty repair or recall, so there's less concern about that.
-The asymmetrical heating of the two valves is believed to most likely be a result of over-aggressive leaning. Quite possibly it's been operated in "flaming dragon" mode as was eloquently stated here. The airplane has been kept in excellent condition inside and out, so it does seem to point to how it was operated rather than indifference or neglect.
-It is a low-time aircraft for its age, but the logs show it was flown steadily over its life and it's been a one owner, one pilot plane that has been otherwise well-maintained. Other than the cylinder issues, all the other squawks found on the prebuy were the typical minor issues they normally see.
-Those two cylinders will need replaced in the short term, so the issue now becomes what agreement, if any, we can negotiate to account for that. My purchase agreement allows me to walk no questions asked, so I'm not too worried about that. The seller is motivated to sell, so we'll see where it ends up. If I walk, the next buyer is going to discover the same issues, so one way or another it's going to have to be addressed. My preference at this point is to negotiate a price reduction to account for the cylinder replacement and have a shop with extensive Mooney experience near me do the work after I take possession.
Again, I appreciate all the opinions and insight. Keep them coming, as I'm getting back to my GA roots flying after 20+ years of military and airline flying and this is my first aircraft purchase adventure.
Thanks,
Tom