If I were you, I'd try looking at your problem in terms of how your snatch is comparing to a split jerk. Make sure you're pushing yourself into the right position which is torso inclined slightly forward to get the proper overhead lockout position. Back foot should hit slightly before the front so that you can push yourself into the proper position better. Get a video and look at your legs. Is your front shin inclined forward? That seems to encourage a backwards lean of the torso.
At least, that's assuming that all the basic components of the normal lifts apply to these variations as well (and Olympic lifting is fairly consistent).