I'm enjoying watching your progress with this. My TR6 also has a mix of push in and screw in injectors, not an issue. Personally I'd replace the injector pipes if you don't know how old they are and definitely fit new O rings to the injector adaptor blocks. TR Trader (Prestige Injection) will sell you all these at decent prices. A pain ordering stuff in UK after Brexit. I live in Germany so tend to pick things up when I'm over there to avoid that hassle.
If your injector pipe leak is right at the elbow you may be able to shorten it slightly and force it back on. The workshop manual describes the process.
Good luck!