In SCCA Solo II autocross, you will be put in C-prepared class. Those cars run 10" wide or 12" max wide rim depending on classification for your car. I think it's 12" for a 68 Barracuda, but check the solo II rules online about that.
That sort of solves your bad front fender issue. Just flare or cut them for wide tire clearance.
I have a picture of a 67 Baracuda C-Prepared car. But not on this computer.