I would also highly recommend one of Jack Sim's gas pump guides.
Although it is out of print and hard to find, I think the "PCM's Guide to Gas Pump Restoration" can be a great resource. While the restoration step-by-step is kind of generalized, the 1000 pictures of gas pumps in different brands and grades over the years is invaluable. Knowing the proper color scheme, pump plate sign or decal and ad glass can help you do a historically correct restoration.
Petroleum Collectibles Monthly's e-book Gas Globe Guide
is the authority on gas pump globes, values and their company history.