Richter, the rigs I learned on were 200# Mono and 7 feet long. I still use this length. Most billfish and big game leaders are 7ft. For billfish you use a combination of several sections of leader of different types.
Lighter Mono leader can be used but all of our jigs fish either standup or handline. On the Handline you need a heavy leader or you will lose gear.
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"Never mistake motion for action"
— Ernest Hemingway
"thud!"