Drag Radial or Slick

I recently bought a set of 15x8 steelies for my 1972 Dodge Dart. I'm looking to buy a set of used drag tires (slicks or radial, either is fine) for the rear. I really don't think I can fit anything bigger than a 9 inch tread. I have stock springs and stock wheel wells, but the rims do have the proper backspace. I'm still a little bit concerned about fitment and rubbing, I know some of you on here have a lot of experience in that department, but I'm clueless with this stuff. So any extra tips or knowledge regarding how big of a tire will fit, would be greatly appreciated! I have cold green cash for the right tires, and can pick up anywhere near Chicago or Indianapolis. Thanks in advance guys! :cheers: