Is my post being seen. I have got no replies?

I have a 85 bronco with a 351, 5.8l. I want to swap to a GM hei distributor. There is a red and green wire on the old coil. Once I spliced on to new pigtail for the hei, the tach pegged all the way over. Does any buddy know how to correct this so I can use my stock tach ?