Sizing for 64 Dart 270

My rears in that photo are 245/60-15 on a 15x7 rim and fit easy-peasy. Lots of room on both sides.

In case nobody told you yet, it's a good idea to do a mock-up and take LOTS of measurements before you buy anything. These cars have a variance factor so what fits one may or may not fit another, even when they are the same year, model, etc.