I cheated and had my calipers bead blasted... cleaned them up real good!!  I have a lot of nice caliper parts if u need any... I would buy new rubber seals though... but i have good pistons, and freshly zinc plated banjo bolts, bleeder screws that look brand new if you need stuff... but no.. as he said not very difficult... I thought the hardest part was getting outer seal in after the piston....