Assuming communication issues and a desire to not alter timelines in a way that'd negate my existence, I'd pick more contemporary figures.
1. The entrepreneurial grandfather I never got to meet. Difficulty: should do it in the couple weeks before he was killed in a car accident and without giving away who I am.
2. Seduce the secretaries of the founders of OptionsExpress when they are at their most vulnerable so I can get a head's up on all their bigger naked short plays and just play into the early stages of the pile-on without the SEC getting on my ass.
3. The great-great-great grandson I may one day have that'll want to meet me. Future Cygnus may already be trying to contact me, so I take those casual coffee shop business conversations seriously bros.
Just kidding, I'd probably screw up the calculation and end up somewhere in deep space.