Rebuild kit: This can be ordered from several vendors and with or without the bellows. This was the cheapest kit I found with the bellows and they are a reputable company. SKU khbellowkit, https://www.powerbrakebooster.com/

Cad plating: The original plating is yellow cad(mium) #2. When you go to take the front and rear plates off, you'll see the original color where it was protected by the elements. I used The Chrome Shop in Menasha, who has done chrome work for me before. They had the plating done and back out the door in under a week. Note that there is a $200 minimum order charge, so you may want to throw in other parts if you have other stuff to be yellow plated. https://the-chrome-shop.com/services/

Disassembly and reassembly: Besides the factory shop manual, I used this video as a guide. However, since they only replaced one o-ring, they do not show that there are two "internal" seals - one inside the copper ball bushing and one at the bottom of the assembly when everything is apart (flip over the plate) inboard of the tin cap. You'll need to get a dental pick or equivalent to dig the seals out. https://youtu.be/FdLblLTVe3s?si=mmRNE8OYQqHDt_a_

Removal and installation from the car: I made this summary video to help make it clear what needs to be done. https://youtu.be/ndgD19VxWtU?si=xdHwuMD8D1faSwoE