15" Rear tire sizes for Duster

Hello, I am ordering 15x8 steel wheels I need to get tires for. They are going on a 1973 duster. I'm not sure what size tire I need. I also need to figure out if I need 4 or 4 1/2 backspace when I order my rims. I want a taller tire to go up into the wheel well and fill it in. Any suggestions?