(I hate to jump in on Aaron, but I will answer.) You should try the Rio 15ft Steelhead & Atlantic Salmon Knotless Tapered Leaders leading up to your sighter. I'm not sure what you mean about the length of your 14lb Golden Stren; as a sighter that should be only about 6in long. If you want more length on your cast, add an additional butt section above the Rio leader using some hard mono like Masons in about 30lb.
That Loop rod is the best all around Euro nymphing tool in my opinion, but I hate to tell you, I don't think it is best for casting the tiny weighted flies. The Greys Streamflex 10ft 3wt actually "casts" the tiny two fly tandem better, especially in French nymphing situations. If there is any downstream wind, casting these flies is nearly impossible and forces you to go with a heavier anchor.