I got some new tiffs today from Joe Holmes at DEQ - they are georeferenced historic 15 minute quads in my study area. They are referenced to NAD83. I haven't tried to create my feature layers yet with them, but I downloaded, unzipped and looked at them in ArcMap. I am regaining hope for the project. Meanwhile, during lab yesterday, I downloaded some modern maps that I was going to try to create polygon layers showing the shoreline changes and sandbar development.
I'm going to go forward with the maps Joe sent me. My cohort in crime, Jim Delahoussaye, will go to Joe's office tomorrow with an external hard drive to copy all the historic maps that Joe has on the Atchafalaya Basin area.