Thanks for the info about the stanchions and cabin liner, msmith, I'll check it out before we make a final decision.
The Yanmar on the C&C doesn't have an engine hours meter, so we have no way of knowing how much it has been run. It looks like it's in excellent condition, no signs of obvious corrosion, oil/filters are clean, no drips. But I know next to nothing about this stuff. It's a 2QM15.