I agree that the tach probably shouldn't be tampered with, at least in the manner mentioned here. Looking at these RPM'* vs. MPH listed above, I am not too sure those are that far off. They may be about 200RPM higher than what my '93 SE runs, but no more than that. As far as the 6000RPM @ WOT, I can't comment on that. I rarely go above 3500RPM. I just don't get into the throttle that deep.
Did you try tapping the brake while holding @60 MPH or so? If the RPM jumps up when you do this, then the TCC is working.
1993 Bonneville SE, Purple Pearl...The Deuce
Born On Date: 1/25/93 @14:18
187,000+ miles # Parts Fallen Off=(3) # UIM'* Replaced=(1)
# Transmission Mounts Replaced=(3) as of 11/7/06.