A friend of mine has just done this. He installed 17x8 American Racing wheels with a 4 inch backspacing on a '74 Nova. Same as a '73. I have owned both.
The diameter of the wheel was not as much of an issue as the width and offset. He used 245's on the front and 255's on the rear. The fronts rub the inner fender just a little when turned all the way. On the rear he had to trim the fender lip inside to clear the outer sidewall, and the car had leaf spring shackles on it so he raised it to the next hole from stock. This fit fine and the car looks great.
Hey John Paul, I have 15x8.5 CenterLines on my Nova with J60 RaceMaster DOT street slicks. They are 27 tall and 9 wide. I trimmed the fenders and raised it a little with shackles. No tubs or narrowed rear end. It hooks and runs 12.30's in the 1/4 mile. So there!