Inner and Outer Rocker Replacement

You must be very skilled with metal work to be taking on such an ambitious project - I tip my hat to you! :prayer:

What you really need is the chassis dimension specs diagram - same as what the frame shop would use to straighten out a tweaked frame. It gives the reference datum and all of the dimensions to make sure everything is "squared" up to specification.

Here is one for a '70-'74 Cuda