The term restoration is in my opinion a tough word to put a definite explanation behind. My views are probably in the 2% area where every bolt, fastener, piece of tape, paint marking, etc is inspected and refinished. For others, it might be putting the correct valve covers and air cleaner back on the car. As Justin pointed out, when entering into the restoration arena, one needs to know their limits.
Just how far do you want to take the restoration. We all know of people who blow a car completely apart and then it becomes nothing but a collection of parts stored in boxes. Attend car shows and view the cars first hand. Ask questions to the owners. Most will shoot you an honest answer. That was my point in stating previously that anything can look good in a picture, but when you have it in your hand and you realize that there is no way that the dash bezel pieces are going to actually line up with the screw holes without some major grinding.
Secondly, I strongly suggest reusing as much as possible of the original parts. Sometimes that is not possible as those pieces are completely trashed or no longer with the car. When I tell someone that a 69 B-Body ralley dash restoration is $2800 plus, some think that I am crazy and that I am over estimating the cost. But I know that this reconditioned dash will go back together will no issues and different pieces will fit back together as it once did.
We have customers who have cars that have won Gold certificates in OE judging levels to guys who are putting cars together so that they can drive to the local cruise in. A very good customer and friend has just got back from the Chicago MCACN show. Their 69 Dart GTS scored a 990 out of 1000 points, last year they took another Dart and it scored 997 out of 1000. And to top it off, they drive these cars.
To paint a slant 6 car or a Hemi car, the basic body work and paint is all the same. The same goes for most of the interior pieces. That is why I tell customers it does not cost no more to purchase weatherstripping for either configuration. It is just the details that separate the two.
I am not trying to talk down to anyone or scare them away. Just want people to understand what a restoration can involve so that the next time that I see them, they are not completely burned out on the project. And back to the original question, as to where to go for your parts needs, then just trying to alert them to ask questions and verify as much as possible .