will 19x10.5 rims fit decently on the rear of an f-body? I won't need to use spacers or roll the fenders, or do I?

 

If you follow the recommendations in the Wheels & Tires FAQ (sticky at top of topics page) regarding offset for the 10.5" wide wheels, you will minimize the problems. Depending on the tires you put on the wheels, there's always the chance you might get some minor rubbing on the fender lip, or rubbing on the inner fender liners. You also have to check the protruding edge of the bump stop brackets to make sure they will not catch the inside of the wheel rim when the body is jacked up. It appears there is a large variation from car to car in what fits and what mods are needed.