235 is about the widest you're going to fit out back. maybe 245 depending on what rear end and with special considerations to ride height and lipping the fender a little bit.
the biggest issue you're going to have is finding rims in small bolt that are wide enough to accommodate that width tire with that much back space for the rear. basically, you're looking at two or three designs: rallye or cragar SS and some slot mag styles.
further hampering this is that those are by and large 14" or 15" and the tire selection in those sizes quickly becomes the limiting factor of what you can run if you want a matched set.