My disclaimer is I stated the the internet is "close to being an Alice's restaurant". The internet is the place across the street - with a more limited menu.
But speaking of unavailable lines : Paul Gaskell posted about meeting Go Ishii while in Japan and of Go's generosity. Go Ishii stated that it is almost impossible today to find level lines that have enough wiry stiffness, properties that he believes necessary for the lines to cast smoothly and accurately and that they are rarely available today especially in sizes smaller than size 3. He then gave Paul and John two of the last spools of some level line, now discontinued, that Masami Sakakibara had made to his specifications several years ago. Though I don' t recall him mentioning the size of the line. I seem to recall reading about this line on Oni's old blog. Though I wasn't quite sure if he posted about lines specifically made for him or if it was only line he was testing for one of the line manufacturers at their request.
I find the current TUSA level line softer than the Sunline level line. And tend to prefer the stiffer line. Though I can cast either one, and really work to develop the skill to cast either one well, but I don't think I have the casting skill to be able to describe the subtle differences between how the two different lines cast. Or under which situations one might be a better choice than the other. As with most things each has an advantage or disadvantage depending upon how they are used. Long or short line, the type fly used or the rod they are used with.