Rear Tire Sizes

I have a 71 Duster with NO suspension modifications. I'm running 235 50 15's in the rear with spacers (I think they're 5/16"). I hate the "look" and would like to increase the size of the rear tires. I'm just curious, would all you Duster and Demon folks tell me what size tires you're running in back so I can get some ideas? I'd really like to wear some 70's but I'm afraid they'll rub somewhere.