I think you will need a custom set. The 10x15 steelies come with a 5.5 Back Space as standard. I just bought a brand new set from Summit, they are made by Wheel Vintiques.
Just so you are aware upfront the Dog Dish caps fit Really tight on these wheels, so tight that I may need to file the recess down on the wheel some so the Dog Dish's don't pop off when you are driving down the road.