Either take the 1/2"(or whatever it is) off the lower iso bushing or ditch it all and pick up a set of 8-3/4 shock plates and u bolts. 8-3/4 plates are all the same and I see them for sale used anywhere from $50-$100 and new u bolts will run you $25 at Autozone.
Thats not the original rear in your car, is it?