Here's a video we just finished showing how a 914-6 front calipers go back together.
https://www.youtube.com/watch?v=ioDak516MkQ
OK, granted, we did a little dis-assembly, plating and piston prep before we got here but, this will show you how they go back together.
Everyone here knows that we're "HUGE" proponents of plating your calipers. ATE zinc plated the calipers at the factory for a reason. Zinc is one of the best platings to combat rust. 99.9% of caliper failures can be attributed to rust. Your plating has worn off the exterior "and" the interior of your caliper. Water will find it's way into your hydroscopic brake system and, when it does, you get rust. Rust and old fluid form to make a bond and you have a stuck piston. If you rebuild your calipers without plating them, rust will form again in a "very" short period of time.