"Marty from Sunny Florida" wrote
Another option I've looked at is purchasing a low price Cessna with an
engine that's past it's recommended time between major overhaul. Some of the
sellers I've spoken with are insistent that recomended times aren't
important, it's the condition of the engine that matters (ie. not making
metal).

That's somewhat but not completely true. Parts do wear. Having said
that, if we're talking about an O-200 that is high in hours but low in
calendar years (say 2000+ hours in less than 10 years) and is not
making metal, not using excessive oil (anything over 1 qt in 5 hours
would be considered excessive for that engine), and has good
compressions - keep running it. I've seen those engines go for 3000+
hours. I've never seen one fail in flight due to causes that could in
any way be related to running past TBO.

Just realize that an engine won't run forever - you can exceed TBO,
but not indefinitely. It WILL start making metal, using excessive
oil, having low compressions, etc.

I'd like some feedback from people who've purchased aircraft with high time
engines. What should I expect, and what precautions can be taken to keep a
high time engine flying (with the plane attached).

I bought a plane with an O-320 with 2200 hours. I put another 150 on
it the following year. Then overhauled because a bolt was cracked and
the case had to be split to replace it anyway.

Crank passed, cam passed, couple of gears were replaced. Nominal
overhaul. Had the bolt not cracked, I likely would have gotten
another 100-300 hours out of it.

Michael