What you are asking for is called a PPI, Pre-Purchase Inspection. This is coming from a 68 GT500 Shelby owner, considering the value of a Shelby and it's age, the countless counterfeits and shade tree service and previous normal wear and tear maintenance that would greatly effect the value of the car, unless you are extremely knowledgeable, having someone who knows the car is a good idea.
When I bought mine, I spoke to several in the SCCA and looked up a lot on the internet that gave me a wealth of information. The first car I looked at had the entire front end replaces, meaning there were a lot of serial numbers from donor cars involved, then there is a question of what other body work done and quantity of bondo hidden under a shiny paint job. A non- factory radio is no biggie, bit a non original engine block, intake manifold, console gauges can be worth several thousand, a left front fender can be worth mid five figures.
An example, 68 Shelby's were made by AO Smith, they custom ordered from Stewart Warner the oil and amp gauges specifically for 68 Shelby. My oil gauge had been replaced with a generic gauge. After more than 2 years looking, I found a good gauge $200, shipped out for restoration $110, new oil sender, $75, correct wiring harness, $75. and that is one of the lesser expensive parts.