Chillfactor (phil) will be able to tell you more, he's a good caster, he's done some tuition with Terry Edmonds. If you look on YouTube, look up Terry Edmonds and Mark Hutchinson, both are at the top of the game.
I was using 12lb daiwa sensor with esp 45lb shockleader and getting roughly 115 to 120 yards waste deep in water, I'm sure I could of gotten further from the bank.
The length of shockleader I keep fairly simple, from bail are to bail arm. In other words, from the bail arm all the way up to the tip ring and back.