Front to rear, rear solved as long as you turn around the pads. For the front, 6 mm coupling nut, you may have to cut it down to fit inside the steerer, Chinch up the now front caliper with the coupling nut, and use a metric button head cap screw threaded in from the back, a strategic washer and some loctite blue for peace of mind, presto. Use a thin rod as a depth gauge to insure the cap screw and the caliper stub do not come into contact. The result will be slightly stiffer than the typical front caliper bolt.
Check the brake caliper reach first of course.