Just a coupe of things I'd like to point out.
Just replaced all of my caps, rings, lines and GP's this weekend.
Some of the new caps may leak, and not a cause of the O-rings. Sometimes the caps are a little "loose" and will leak no matter how many O-rings you throw at them. Make sure you save all your old ones for this scenario. I ended up having to use an old cap to replace a new one. No matter what I did to seat the new cap resulted in filling up the GP alley within seconds. Old cap, no leaks first try. And NO.... it appeared smooth and perfect inside the cap. Even though I replaced the O-rings with both new in kit, and one's a purchased from McMaster, all leaked with new cap....very disappointing.
Next thing is, those cloth covered lines that come in the kits are junk in my opinion. They become brittle too quickly. I used a multi-fuel line-on just the IP return to #5 Inj- from Kragen when I first replaced everything about 7 years ago. That line wasn't replaced this weekend because it was still soft and pliable, but every cloth covered line broke when touched. Bought appx 4' of multi-fuel line from O'Reilly's(bought out Kragen) and have the cloth line as spare if I decide to ever use it.
Since I did glow plugs as well, I forgot how snappy these engines fire off on a cold frosty morning when both the fuel and GP systems are healthy. 236k miles on the ODO, and it still fires off as if new!!
Lastly.... I'm reminded that the best thing in the world when doing fuel line work is an electric fuel pump. Those leaks appeared without turning the engine on, and the time saved in troubleshooting was nothing compared to having a mechanical pump and all the aggravation that goes with them.
I hope this helps in some way.
Good luck!!!