I use a mechanical tach, that RPM switch looks like the answer for adding a shift light. Would the tach terminal come off the MSD box?
Since the first shift into second gear comes up much quicker than the other gears the shift light set lower makes up for the amount the RPM's climb while reacting. I think if you set each light to say 7400 and reacted to it the engine would overrev first.
Hitting he rev limiter kills more ET than shifting too soon.
