Lots of good advice here, guys.
Most of us have learned the hard way about purchasing these cars. I certainly have. But no more . . .
If you buy an antique car and spend any money at all on it, save your receipts! This includes even the tiniest washer or grommet. Educated/serious buyers LOVE this kind of documentation, without which any "restoration" is essentially meaningless.
Further, it's really easy to keep a repair and restoration journal. Mine lists the date of each repair, the cost, and approximate time spent. On my last restoration project (a '70 GT6) my restoration journal was 5 pages long with more than 100 photos and receipts for everything, including purchases for virtually every nut and screw in the car. No doubt, this kind of documentation will easily increase the value of your car. Money in the bank!
However, NEVER add up the total (superstitious, maybe :e)!
Sure, with some restorations it's obvious if a lot of good work has been done, but for most, if the seller doesn't have excellent documentation we're literally buying a pig in a poke. And sadly, nowadays you can't really trust anything a seller says, unless you really know the seller.
Document your resto carefully, it's worth every single bit of the effort and actually adds to the fun, IMHO. :thumbsup: