When I was looking for a set of skinny 15x6 steelies for mine I ran across a company that makes them...give me some time to hunt that down again....they can alter any two piece wheel...for example if you find a set of 16.5 rally wheels they can replace the center with the old hub cap center style and custom set the back space where you want it.
They can make the wheels for you or alter what you have....