The simple of it is that if you are not happy with the airplane, run.
Yes, I certainly would ask for my money back. The seller mis-represented the airplane to you, knowingly or un-knowingly and should have offered the money back without you asking when the "plane rebuilt" entry was discovered.
If the airplane is indeed nice, in good condition and has been flying all these years, the repairs have proven themselves, however, you need to see the FAA record on it. If the repairs were never recorded on a form 337 this could quickly turn to a can-o-worms, and even if you liked the airplane and decided to go ahead and buy it, its value is signifcantly lowered as a result of the unrecorded damage and when you go to sell, you will either have to attempt to hide your knowledge or it or lose money.
If you are set on the airplane and like it and are willing to take a chance on the radios, make an offer to the seller, a measureably lower price, one you think you could live with come your time to sell, probably in the $17K to $19K range.
Otherwise, retain your A&P for the next prebuy, ask for your $500 back and end the whole deal.
Charles
