Re: The 60\'s
Ruthless, it won't work if you send other people to change the past for you. As long as you remain in this present, history will not change for you. The so called "ripple effect" you see in sci fi movies just doesn't make sense, as far as the physics is concerned.
Your only hope is to go back in time, yourself. In principle, IF you succeed in changing things in 1999 (or 1967 for that matter) and return to 2007, you will return into an alternate present which is the result of your actions. You won't return to this timeline but to a new timeline. You will be leaving all of us behind.
All this, of-course, depends on the assumption that you will be able to change the past. Merely achieving time travel is not enough to make this happen. Physicists have shown, time and again, that the default result of "time travel" is the creation of a consistent time loop rather than a paradox. For example, if you throw a billiard ball into a wormhole and the ball goes into the past and hits itself, it would still go into the wormwhole after the collision.
Note that this is just the default situation. There might be a way to override this, but I am not aware of such a way.