It's not a straight swop. You need the front irons and will have to remove your overrider brackets by taking the trackrod ends off the stubs. At the rear, the factory sell brackets to fit overriders to a car which had full bumpers, but I'm not absolutely sure how it works the other way. Ask your local dealer.
Remember that earlier Plus8's had a full front bumper and overriders at the rear.Some current 4 seaters have the same arrangement because a full rear bumper won't work with a large spare wheel hung on the back.