The 235/60/15's did not have any clearance issues on the rear of the Chevelle. There was plenty of room, it was the front that was limited and it had new stock size springs all the way around. I don't know what the dimensional differences on the Nova are, they might be the same as a Chevelle rear wheel well because the styling is more open on a Nova? But the 215's are a good fit now. I also have 15 x 7's on all four.
Here's a link to a picture:
