1. Give speedway harness part number.
2. Advise how many electrical gauges? Which ones?
3. Do you now have same wire for gauges and for tach? Is that what you said? or it's just going to tach, nowhere else?
4. You added a volt meter somewhere?
5. Using original gauge cluster? If not, explain.

After answers, I will advise a plan.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn