1973 Dart Sport 340 Sunroof question????

Interesting note in this month's Mopar Muscle....regarding narrowed rearends from the factory. The Blue Duster article says that 340 Dusters and Darts came from the factory with Narrowed rear axles. First time I have ever heard that. It says a couple inches.....which means some pretty beefy back tires are possible. From your experience....What is the suggested max tire size for good grip and great stance????