Well, for those who are following my aircraft purchase sage (son to be released as an epic motion picture;) ) here is that latest update.
I found a 150 that looked to be in good shape. I had it taken in for the pre-buy, and I got the results today. It's a 1967 with 2800 on the tach. Well, it turn out that the tach may have been replaced and it may have 5100 hours on it.

The mechanic thinks it happened in 1974, well before the current owners.
There are the usual assortment of well used parts that may need replacement. The landing gear has pulled some rivets and they need to be replaced. The owner has been running autogas, but the STC was only done on the hull. He thinks it was originally done on the first engine, but not on the second. And it has a full load of autogas in it now. (I plan on using 100LL.)
With parts and labor, he estimates that there will be about $4600 worth of work to be done on the plane.

But with that work, he thinks it will be a good plane that I can get a lot of years out of.
So far, I haven't talked to the owners. I am inclined to go with the plane, but I want to talk to the owner about what has been found. The one owner has done a lot of his own maintenance, but I want the work to be done by the people who did the prebuy. Any thoughts?