PatM -
Jeff's comment might need to be considered if you will be working with reproduction brackets. Reproductions are possibly not exactly the same as originals. The brackets on my truck are the same brackets that were used by Ron Wade when he decided to copy 37 Chevrolet pickup truck brackets. That's not to say the others aren't as good, but you might want to allow yourself some "wiggle" room for your layout of the brackets, or better, get the brackets before you move on the the next item on the list.
Just trying to help! Good luck!