I am definitely not an expert but when I purchased my 68 coupe I had the same questions. First I determined if the car was complete and numbers matching. I purchase a catalogue from Year One and found that it was an excellent source of information. It explained what to look for, where to find VIN/serial numbers and what it would cost to replace any missing items on the car. Next I had the car checked by a mechanic/ body man friend who really knows older vehicles. I then searched the Internet for sites that could give me an idea of the resale value of a car in the same condition as mine. I found that Hemmings (www.hemings.com) was a great place to search for selling prices of older birds. Last, I found that this site has been an excellent resource for a lot of questions I have had so you are in the right place.