JNewm
True Classic
About to head down to try to tackle this, but first, a quick question: are the flare nuts (and the flares themselves) the same for going into junction #7 as they would be for different lines in the hydraulic system?That junction (#7) is really easy to get to when the engine/trans are out of the car. It's pretty tight otherwise, but doable. If the lines up to that point are good then there is nothing wrong with only replacing the two from there rearward. Be sure to thoroughly flush/clean the remaining lines before adding the new ones. Personally I would not recommend doing a "splice" somewhere in a brake line, although I know it has been done successively many times. I just prefer to have as few joints as possible. So I think replacing them at the junction block is a good approach.
I have a good condition front right brake line that I may try to bend into shape for use on the back left into that junction, if they look reasonably close once i pull the old one off. The front right line already has flare nuts/flares, therefore allowing me to avoid the need to buy a set of line tools (without a garage, tool storage is becoming an issue!).