I had a 15x7 front with a 235x60x15 tire with a 3-5/16 backspacing. This is just like your front combo. I like my front low and it rubbed going around turns while going into "curb" driveways. I had to puti little 215x60s in the front, like yours, to keep from rubbing, but they looked small. I did not have the hemi-type bulged fenders, so yours might not rub.
Your 255-70 rears are wide but also tall so might fit if you only run the 7" wheels, but those look too skinny for the drag look.
When choosing wheels remember e-body 7" wheels had a 4" backspacing. You usually have to go both ways as you widen them. Like the 8" rallyes for example. You added an inch, but split it by adding half an inch to the back spacing and half to the front. That's why an 8" wheel with a 4.5 backspace fits so well. A 9" wheel shoulg have a 5" backspace.
If you choose a wheel on looks, it'll probably have the 3-3/8 backspace, it'll probably also rub and you won't be happy.
Rob