I just purchased the install kit from Merchant. The $200 one. The only thing I didn't use out of it was the orings for the cups. Mine stayed in. You use silicone for the top valve cover. The bottom valve cover rubber gasket is supposed to be reusable. The kit will come with everything you need though. I just went ahead and bought it cause I didn't want to take the chance of my truck being down for longer because of a bad banjo bolt seal or a oring I didn't have.
I highly suggest you get your injectors from Lincoln Diesel. A whole set comes with the AL return line banjo seals and O-rings for the injectors. Other than that you should be able to reuse your bottom rubber valve cover gasket and the top uses RTV sealant. You shouldn't need anything other than that IF your cups stay in place. If they come out you will need the O-rings for those but can be bought locally.