Need help with vibration!!

Are you sure it's not a misfire condition that is giving you the sensation of a vibration? Is it worse under load?
If I'm reading this correctly you're saying that it's RPM related & not MPH related. So that would suggest it may be engine related. I have to admit that your engine balancing combination sounds very odd to me. I certainly would have opted for a different way with that. I never heard of balancing an engine in 2 halves.