100% agree with Stewart. Using a level wind on a multiplier for casting will greatly restrict your distance. Shock leaders are a must for power casting, so if you want to cast further dismantle the level wind system (very easy job) and practice casting without it, as in the last reply. If this isn't an option for you and you want to leave the level wind on, then why don't you ditch the shock leader and use heavier line straight through.
As for a leader knot, then I would recommend a tapered leader which can be cut to the same dimension as your main line. I then use a four turn blood knot trimmed right down. Others might not agree, but I have always found this very reliable.