Mike,
I used many different books and magazines to source information from. The Master Parts Catalog (MPC) is what Ford Dealers used to look up part numbers for replacement parts. The MPC was available through your parts dept. in print and maybe still is. They are now selling on ebay in CD format. It is a great resourse, but you will have to learn about the part numbering system ford uses.
Mustang Restoration Guide by Tom Corcoran and Earl Davis, uses alot of diagrams and info from the MPC, including the spring charts. I also referenced the reprints of the factory assembly manuals- paint daubs on parts are commonly referenced. The Mustang Club of America rule book is also a good guide. I also searched out unrestored cars (junkyard) looking for different marks and inspection stamps.
The BIGGEST reference was my own car, I only added a few marks that I did not truely find on my car. One being the Paint Inspection Stamp and I found an original unrestored car 51 numbers off mine with the same scheduled build date. Like Russ, I thought that was close enough for me.
For my restoration all original parts were rebuilt and reused. Although things such a the Master Cyl., Brake Cyl, P/S pump, etc. are still available manufacturing differences exist. Although a bit more expensive, I believe, a more correct restoration.
