A buyer from Oregon put down a deposit without looking at the airplane or the records.
Steve, I am very sympathetic. I just bought a 172. It is my first plane and I am having a similar experience. As "rookie" buyers we are advised to treat a potential purchase as "guilty until proven innocent" lest we be stuck with someone else's expensive problem. Yet, there are folks who will come along and just put down the money and ace us out of a plane.
My compromise recommendation (this is what I did) is to have an A&P check the logbooks. If he/she doesn't advise running away, then put down a deposit at that time and complete a purchase agreement making the sale contingent on the results of a more complete inspection.
Based on what you have told us already, it seems that you really had all of the information to make a basic go/no-go decision about a deposit. In other words, you should have your own personal criteria for whether such properly documented major repairs are a deal breaker or not. I understand that you are more technically saavy than the average buyer, but it does not seem that your own personal inspection would really give you enough addition information about such major repairs to tip the balance either way.