A Body Disc Brake Swap 101

Those are my front wheels. I started a thread on the NEW steering and suspension Forum . These rims appear to be 7 inches wide( I haven't got a good caliper so I am guestimating ). I beleive the diameter should read 25.5 inches. According to other responses on the steering and suspension forum this is not a simple conversion.
I now have 8.5`s on the back of my car, would like to have some fronts to match , but 7'' is the narrowest ones they made , maybe 6'' , but I dont want that much weight up there .