1967 Cuda FB project

Getting better view of bottom rear of car to see which way I can go to mini tub or larger. Want to be able to get Viper sized rubber under this car....:burnout:
I will get a better pic of the rear rails, but it looks like one could move the factory rails inboard 3-4 inches at least and reweld to the floor. I would remove the spare tire well to do this. Monster tubs with factory rails????